“PC won’t start”

The friend explained that their PC wouldn’t start up.

“Where do you keep it?”, I asked.

‘On the floor’, was the reply.

“You need to give it a clean, it’s full of dust.”, was my psychic reply.

This friend keeps multiple pets, dogs/cats/birds/lizards.  The poor PC was sucking all the assorted animal dust/fur off the floor, for the last two years, and finally gave up.

So they cleaned the PC, and it still wouldn’t start.  They passed it over to me to look at.  When I opened the PC case, the video card cooling fan looked like this:

dirty card

(yes, that’s dust which has defied gravity and managed to bind upside-down to the heat-sink)

So I pulled the PC apart and cleaned it.  Slowly re-assembled it, and it all worked.
(and the PC spent the next 2 hours applying Microsoft Windows updates, which it hadn’t done since May last year.)

When I gave the PC back, I noticed I’d missed a spot. Sad smile

The Case Of The First Problem Revisited

“Have you got any idea on why this stupid postscript driver for the digital printer/copier keeps spitting out the output below?”

Postscript language dump

‘Yes, the printer does not have the postscript option fitted, and is dumping out the raw postscript language code.’

It’s a variant of the “Case Of The First Problem”, where we had a customer order a printer without the postscript card* fitted.

* – I say card, but most likely these days, the postscript option is installed, but requires an expensive visit from the copier tech to enable the option.

Internet Explorer has issues with session cookies, fancy that.

The problem was reported thus.

Internet Explorer is not storing session cookies for XYZ website.  The session cookies are stored when we use Firefox.

Two hours later, I can tell you that:

  • I learnt more about web cookies than I will ever need to know again.
  • Firefox does things differently to Internet Explorer.

Gentle reader, Session Cookies are cookies which only exist for the time which your web browser is open for.  They are deleted when you close your browser.  They are often used to cache your user name and password.

If you don’t have your username/password cached, you repeatedly get prompted for it.  Which is annoying.  Hence the need for session cookies.

So I started investigating the cookies not being stored issue..  The first thing I noticed was that Internet Explorer wasn’t even bothering to write the cookie down to the local hard disk.  So I broke out the network sniffer (Wireshark).  It didn’t tell me much, as all the web traffic was encrypted.

The next step was to load up Fiddler, the Web Debugging Proxy.  Fiddler allows you to inspect all the encrypted web traffic between your computer, and the rest of the world.  The session cookie that the XYZ website was trying to push down, had the following details:
Web browser cookie

There are two issues with this session cookie:
Cookie - Expires Parameter

  1. It sets an Expires date.
    This normally means that it is a Persistent Cookie, and not a Session Cookie.
    In other words, we should not see Expires in a session cookie.
  2. The Expires date was set to a date/time in the past, which is not supported behaviour either.

So why does it work with Firefox then? – Firefox seems to be treating the expired Expires date as no date at all.  So it defaults to a Session Cookie.

Internet Explorer? – A bit more complicated:
cookieprocessing.jpg

 

 

 

 

 

 

Some further reading:
The Unofficial Cookie FAQ
Wikipedia HTTP Cookies

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The case of the broken Microsoft Word VBA application

It was a Microsoft Word (VBA) application written back in 2001.

Essentially what it does is:

  1. user selects a letter type.
  2. the user then enters some customer reference numbers.
  3. the VBA application does an Oracle database lookup to convert those customer reference numbers into names and postal addresses.
  4. which the VBA then uses to “mail merge” into whatever number of letters need to be sent out.

And it was broken.

I had a feeling that writing about patch management policy would come back to bite me (and it did).

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The SMS Mirror Driver

The SMS Mirror driver is the root cause of the problem, with help from a dated video driver, the SMS Remote Control application (Wuser32.exe), and an unsupported operating system (Windows 2000).

So what does the SMS Mirror Driver do?:

Video acceleration significantly speeds up your Remote Control sessions clients.  For video acceleration on clients running Windows 2000 or later, SMS uses a Mirror driver.  The Mirror driver can simultaneously display the same output to several video devices and has no dependencies on the client’s video driver.
– Microsoft Systems Management Server 2003 Operations Guide.

We received a fault report:

My desktop icons are grey colored.

It took some investigation, as the customer left out some details.  Here they are:

  • the problem was occurring on a system they were remote controlling with the SMS Remote Control application.
  • it was an intermittent problem.
  • it was in a development environment.

Continue reading

The printer does not print “Watermarks”.

The problem was described to me like this:

Lexmark print driver showing WinPrint processor selected

When you print to the network printer, and want to use the “URGENT” watermark setting, it does not work.
When you print to a locally installed printer, it works.

The answer?
When I install the printer driver on the Windows Server I specify WinPrint / RAW as the print processor.
When you install it yourself, on your PC, the driver picks its’ default (in this case LMABT54C), and the Watermarks feature works.

So why do we use WinPrint / RAW on servers?
It’s a known quantity.  In other words, I know it works (mostly), and more importantly, as it’s a user-mode DLL, it is stable.
I don’t want some crappily written HP or Lexmark DLL* crashing my print server, or Citrix server, thank you.

Further reading:
Basic Printing Architecture (Ask The Microsoft EPS Windows Server Performance Team)
Disabling Advanced Printing Features (Ask The Microsoft EPS Windows Server Performance Team)

* – in this instance, it was a Lexmark Universal print driver causing the problem.  Given the build quality of the Lexmark printers I’ve seen, I wouldn’t trust their software drivers.

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3 fools and a printer.

Konica Minolta C652 Control Panel Problem:

Konica Minolta C652 multi-function printer, with Fiery RIP installed, refuses to print.

Cause & solution:

If you leave the Fiery RIP Controller in Setup / Menu mode, it stops the printer from printing.  You can tell the Fiery RIP is in this mode by looking at the item circled in the picture.  It should read “Info”, and not “Functions”.

It wasn’t obvious to us, so we called a Konica tech out.  It took him 1 minute to work the problem out.  We’ll not make that mistake again.

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Printer jams

Lanier c2800 & c5000 colour photocopiers and printersI expect that, when a fault is logged though to me to investigate, that some troubleshooting has been done.

Printer jams.  Vendor technician has thoroughly tested printer.  I think it’s a driver problem.”

And that was it.  No other details.

What did they mean by ““Printer jams?””.

Is it physically jamming?

I’m never seen a printer driver cause that.  Perhaps it’s stopping mid-print.  ie. stopping at page 10 of a 20 page document.

I bounced the call back, as there was not enough details.

I’ve heard nothing further since.

Physical printer jams are caused by one of four things:

  • Incorrectly loaded paper trays.
    (Lexmark Optra’s were infamous for this.)
  • Non-laser printer paper being used in a laser printer.
  • Paper stuck in the printer’s paper path.
    (this is caused by failing to remove all the paper from a previous jam)
  • Paper not stored in the same environment as the printer, being used.
    Changes in temperature and humidity can cause paper to jam.

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“There is something wrong with these files …”

The desktop technician solved the problem himself, with the comment

There is something wrong with these files …

but didn’t realise it.

Microsoft PowerPoint XP was crashing whenever the customer was trying to open a particular set of files.

Google should have been his friend here.
aka Let Me Google That For You : Powerpoint crashes when opening file

The first link, PowerPoint crashes while opening certain presentations, has the answer.

“Since you can’t tell from within PPT whether an image was RGB or CMYK, you’ll need to go back to the source image files to verify whether this is the problem. Using PPT2003’s Save Image As feature, you could save the image as PNG or JPG, re-import it and delete the original. The presentation should then open in earlier versions of PowerPoint.”

PowerPoint does not support CMYK very well.  No surprise there.

So how do we tell if a PowerPoint file has a CMYK image in it, if we can’t open it?

If it’s a PPT file, in other words a PowerPoint 97-2003 format file, to confirm the issue we can use Notepad, and search for CMYK.
cmyk in a powerpoint file

If it’s a PPTX file, in other words a PowerPoint 2007+ file, and you don’t have PowerPoint 2007, you could try the following.

  1. Rename the PPTX file extension to ZIP
    powerpoint 2007 icon –> powerpoint 2007 extenstion renamed into zip
  2. Open the file with your favourite archive program.
    pptx file contents
  3. Search for the offending image, and replace it.  Or delete it.
    (no, I don’t know an easy way to find the offending image, sorry)
  4. Rename the ZIP back to PPTX, and then that should fix your issue.

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SSL errors, and how to diagnose them.

Frankly, I don’t know, but here’s what I learnt.

It started with a customer reporting a problem

When we press the publish button on the website, we get a 403 error.

A co-worker of mine picked up the call.  After trying many different things, he asks our Network team for help.

If it works on a standard Windows PC, we’re not interested in even having a look.

“What next?”, asked my colleague.

Never, ever volunteer; but the words sprang from my mouth,

“Perhaps I can be of assistance.”

SSL Malformed Packet Some network tracing was done, and the problem was SSL related.  An SSL error was being thrown.  The application server was throwing a SSL Malformed Packet back at us.

As SSL traffic is encrypted, you can’t tell much more than that, unless you turn off encryption.  Not going to happen on a production system.

My first guess at the solution was wrong.  An schannel.dll update didn’t fix the problem.  I spent a bit of time analysing what the JavaScript code was doing as well.  Couldn’t find any issues with it.

So what else do we see in the network trace?  Ah… we’re getting packet fragmentation.

Hmmm.

Told my colleague to look at the PMTU Discovery setting and to turn it on, to eliminate the packet fragmentation.  That was wrong too, as it was already on.
But turning it OFF fixed the issue.

So what are the important “take-aways”?

  • Sometimes your first, second, and even third guess, can be wrong.
  • Sometimes you need to cut your losses with an issue, but in this particular case, we did not get to that stage.
    IMHO, I thought we were close.
  • Know what is “normal” behaviour, and what is “abnormal” behaviour.  Spot the difference.
    In this case, we had two network traces; a working one, and one which captured the problem.

Update 4th Oct 2009: Eric Law’s MSDN Blog post is worth a read: Internet Explorer Cannot Download https://something
Update 6th Dec 2009: Deb Shinder’s article is worth a read: SSL Acceleration and Offloading: What Are the Security Implications?
Update 17th Dec 2009:
I had to revisit SSL sniffing in Internet Explorer has issues with session cookies, fancy that.

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