Following my problems with the BSOD I did a bit of searching and have found out how to fix that particular problem (I hope!)

My main issue now is that my laptop won't switch on to give me a chance to fix it! At various stages of the start up process I get the previously mention BSOD saying the usual "kernel stack inpage error" and "beginning dump of physical memory".

On a good day it will actually let me log onto windows but before it can start up properly (even before I started getting the recent problems it took ages to start!) I get the BSOD again before I can do anything.

Any suggestions on how I can get my laptop to start up and stay on long enough to let me try and fix the error?

Did you try Safe Mode? Make sure any extra devices are removed too. If more than one memory module, remove all but one. Swap out to eliminate any as cause - be sure to touch an exposed mounting screw or exposed metal of the chassis to discharge any static in your body, then make sure you do not touch the contacts of the memory modules.

I have tried safe mode but got the same result as trying a normal start up.

I have no idea about the memory module! I probably should have said in my first post I know very little about computers so if it involes anything more than a few clicks then I need the idiots guide!

I decided to try again last night and it managed to switch on! And stayed on long enough for me to rescue a few documents (photos and such like) before returning to BSOD.
I've found that once I get BSOD it won't start up again unless I leave it for a day or two.

Well, that sounds like a heat issue, and letting it cool down completely allows you back in, until it heats up again. You might try opening the side panel and make sure it is free of dust and dirt. Be sure to touch bare metal of the case before reaching in to discharge any static in your body.

While in there, Inspect the motherboard for bulging or leaking electrolytic capacitors. These failed or failing capacitors are a common cause of sudden, but seemingly random system lock ups and reboots. The capacitors look like tall soda cans, many of which surround the CPU socket.

All older motherboards, and many of today's less expensive motherboards use electrolytic capacitors containing a liquid electrolyte. Failing (including flawed and/or abused/over-heated) capacitors literally bulge at the seams due to excessive internal pressures. Extreme (and very rare) cases result in a firecracker type explosion that can really stink up a room. Typically, electrolyte just oozes from the pressure relief points stamped in the tops of the capacitor casings (seen as a symbol or letter). The electrolyte can be caustic to motherboards and flesh. Look for white to dark-brown, dried liquid or foam on the tops or bottoms of the capacitors. Bulging capacitors are a sign leakage is about to occur.

A motherboard with bulging or leaky capacitors can be repaired, but often it is more cost effective in the long run to replace the motherboard.

Be sure to first power down, unplug the computer, and keep yourself discharged by touching the bare metal of the case.

Leaky Caps:


Bulging Caps:


If all looks good, blast a desk fan into the interior, boot up and see if it holds. Peek inside and make sure all your case fans are turning too.

This could also be caused by a weak or failing power supply, or bad memory. You can test your RAM using one of the following programs. Both require you to create and boot to a bootable floppy disk or CD to run the diagnostics. Using the floppy method is generally easier and yet another reason I still include floppy drives in my new PC builds. However, the CD method is just as effective at detecting RAM problems. Allow the diagnostics to run for several passes or even overnight. You should have no reported errors.

Windows Memory Diagnostic - see the easy to follow instructions under Quick Start Information.
or
MemTest86+ (for more advanced users) - an excellent how-to guide is available here.

I have actually had someone else suggest that power might be the problem. My laptop is 5 years old now and the battery isn't what it used to be! I can't really leave it running off battery power for any lenth of time so I always run it off ac power so that should be ok shouldn't it?

I used to have a terrible problem with it over heating but I replaced the fan a few months ago which seemed to solve that problem.

Due to age I think what you said about the capacitors is definitely worth investigating so I will check that out.
Problems with the RAM also sounds about right as I've been told this is what could be causing my BSOD. I have also been told to change my virtual memory, although I've not been told what to change it to! Is it just 1.5x the RAM?

I only have an external floppy drive. Would this make a difference when trying to boot from a floppy disk?

Sorry for all these questions and thank you for your help so far!

Oops! Sorry, I missed in your opening post this was a laptop - inspecting for leaky capacitors on laptop motherboards is not something done by users.

As for your VM, 1.5 x RAM is the typical starting point - but more may be better if you have small amounts of RAM.

If you can tell your system to boot to the external floppy, it should work.