In case you haven't, search for that unhelpful string in quotes and you may find archived information at least to get an idea of where to start.

Does it boot directly to BSOD ? or is it every time you do something in particular ? ..if the latter..What ?

It boots, and fails sometime, anytime, especially when in the middle of something, anything, nothing in particular. :(

No known changes made to the computer for a few weeks, unless one of those dreaded auto-updates started in stealth mode. I have most of those turned off, but there are some that it's very difficult to stop going into auto mode.

Do you have a spare "known to be good" power supply that you can "swap "in"..? XP likes stable power "rails"..even a small / tiny difference/ fluctuation in voltage will BSOD ..

Do you have spare "known to be good" RAM that you can swap in ?..bad or dying RAM can also give random BSODs ..are the contacts of the RAM bars clean and making good contact ? or are they oxidised ?..

How many RAM slots has the MB got ?..how many are in use ?..Try switching a "RAM bar" ( that you are currently using ) into a "free" RAM slot..

Only swap in or change one thing at a time..

I always prefer trouble-shooting the hardware before looking at software problems..checking / substituting hardware is fast, and in a machine that has always run XP, some of the hardware is now getting old and maybe tired..

What are the machine hardware specs..

Easy test to see if it is hardware problem..boot a live linux disc in it..if it crashes or freezes while you are using linux, it is a hardware fault..Use an old version of Ubuntu or Mint..presumably you have 86 architecture ..Mint version Gloria 86/32 will run, and will recognise virtually all hardware, sound cards , graphics cards etc ..

Thanks
I'm going to pull the machine apart, again, over the weekend to check for physical problems.
If it isn't going to be obvious the machine may be headed to recycling.

Is the hard drive nearly full or does it have more than 50% space available?

Having troubleshot more than a few BSOD's I can add this:

Look for newly updated or added drivers, esp video or printer. Is the page file set to fixed or dynamic? Recreating it after a defrag might help. Sometimes changing to fixed helps on machines with a low amount (<2gb) of memory.

Microsoft has a LOT of resources on the TechNet Knowledge Base to troubleshoot these things but moves them around a LOT. Search on the Microsoft site NOT Google to find the error strings recommended solutions. Expect to find multiple pages that sometimes slightly conflict in their advice.

Other times as martinibuster has alluded to it can be free space related. Not quite 50% free is needed but XP systems do tend to get cranky when less than 100 mb is free, esp if it is fragmented.

Old school time honoured glitch fixes might help too like cleaning up temp files, defragmenting the whole drive and doing a drive wipe then a refresh reinstallation.

Thanks for the additional suggestions.
The system has plenty of free hd space.

Here's where we've arrived at now.
It appears that one of the RAM boards has developed a problem. I identified it by a process of elimination. Although there is now 1GB less RAM on the system, it no longer has the BSOD. However, the crash has resulted in another problem of corrupted files, somewhere. I fixed those.

svchost keeps crashing and closing all networking. I've been through TechNet and there doesn't appear to be one fix that solves the problem, so i'm going to have to keep working through them.

I'm seriously considering pensioning off this XP test machine as there only so much time I can invest in getting it working for the benefit of my customers.

I may try a few more attempts before then.

Thanks again for the encouragement and advice.

It appears that one of the RAM boards has developed a problem. I identified it by a process of elimination. Although there is now 1GB less RAM on the system, it no longer has the BSOD.

Despite the fact that only one RAM bar has a problem, replace RAM bars ( this will be "old RAM" type DDR2 or older I expect on a machine running XP ) in "matched pairs", from the same manufacturer..XP does not like "mix and match" RAM..or just use one RAM bar of 2 gigs ( seems like you might have been running 2 x 1 gig before ? ) if the MB will support that..

they were 4 x 1 gig boards
It's not worth buying new ram at this stage, especially if i'm going to pension it off.

In that case ..try a linux live disc on it..( see above for which "easy linux versions")..it should run OK ( or even very well indeed ) on 3 gigs RAM..
If all is OK then do a "side by side" install of linux with your XP..

Linux will be able to "see" your XP installation and all of the files.

Then install wine..( do this via the linux software manager ) ..then "mount" your windows partition, navigate to the .exe of the software that you want to run, right click and choose "open with wine"..if you are lucky :) whatever software ( eg photoshop CS6 and previous will run under wine ) you are keeping the XP box to run will be able to run via wine under linux..

In some cases, the above may not work, and you may need to "install" the windows software via wine while you are in linux ( do this with the XP partition " unmounted" ) if the software installs via wine OK you'll get a shortcut..right clicking on this and choosing "open with wine" may well work..sometimes you'll get various error massages, keep clicking through them..see if the software actually runs..

BSOD?

Curious, I haven't seen that for years.

Have you considered backing up whatever, then do a clean re-install?

I have two machines in the family which I am refurbishing, upgraded CPU, upgrade RAM to max 2GB. One is an HP Compaq Desktop, the other a Dell.

The first one, I've done the CPU and am still awaiting RAM, BUT I did a clean install of XP Pro which required [from memory] 133 updates.

Sings to me now - even with only 768 Mb RAM.

In the "Idiocy" department, a glitch. The HP driver for the LAN port doesn't work. Dunno why? A friend suggested trying the Dell driver. That worked like a charm.

OK why?

Why spend good money on a machine for older family members to send email, photos etc. look around the internet?

HP Compaq cost so far is $A35.00 plus my time having fun and a challenge.

The Dell likely will cost $24.00.

Consider a clean re-install

Thanks.

This recovery project has taken a back seat as i've already spent too much time on recovery.

Since removing what appeared to be a faulty RAM board, it's now only a problem of damaged files.

A clean re-install, i'm sure, will get it working again, but then, i'm going to have to dedicate time to restoring the software. If this were my home machine, or if it were a machine required for specific projects, i'd certainly spend more time on it. It's not actually required for anything specific, and any data is already quite safe.

I'll get back to it in due course.