OK, some generalisation of the problem:
[ul]
[li]It mainly happens on AMD & NVIDIA & DDR & XP setups, but there
are exceptions. (ockerb, see Aug 6 - that's a PIII)[/li]
[li]A lot of it is incompatible hardware. I have read microsoft info on all these errors, here are short summaries:[/li]
[ol][li]PAGE_FAULT_IN_NON_PAGED_AREA (STOP 0x50). This means that something tries to access memory it shouldn't. Suggested cause - incompatible hardware or drivers.[/li]
[li]IRQL_NOT_LESS_OR_EQUAL (STOP 0x0A). Again, accessing the wrong memory area. Suggested cause: driver problems, hardware problems.[/li]
[li]DRIVER_IRQL_NOT_LESS_OR_EQUAL (STOP 0xD1). This doesn't seem to be widespread. Microsoft say something about RAID and USB and that it's fixed in SP1.[/li]
[li]STOP 0x8E (no special name). Not much about this error. Suggested cause: faulty RAM.[/li]
[li]STOP 0x7F (UNEXPECTED_KERNEL_MODE_TRAP, although this sometimes isn't displayed). Looks like Microsoft don't know

but they think it's hardware fault. In this particular case (unlike in 0x50 or 0x0A) they don't think it could be software or drivers. I recommend reading Q314102 article in the Knowledge Base[/li]
I get all of these errors from time to time. The following errors I don't get but they are mentioned in this thread:
[li]MULTIPLE_IRP_COMPATIBLE_REQUESTS. No help on Microsoft Support[/li]
[li]BAD_POOL_CALLER (STOP 0xC2). Another one of those 'driver accessing memory incorrectly'. BUT this one has info to locate the driver. Knowledge base article Q314492.[/li]
[li]PFN_LIST_CORRUPT. No help on Microsoft Support[/li]
[/ol]
[li]Service Pack 1 for XP may fix some problems but not all.[/li]
[li]Downloading latest drivers may fix some problems but not all.[/li]
[li]The STOP may occur in nv4_disp.dll or win32k.sys (seen both myself). But usually it doesn't say where it is.[/li]
[/ul]
Trying to solve this by elimination:
[ol]
[li]Install all software upgrades. This includes WinXP SP1 and new drivers. This doesn't help me -> it's probably hardware.[/li]
[li]Disconnect everything I don't need. Leave: Mobo+CPU, RAM, HDD, Video card. Still crashes.[/li]
[li]Replace my AGP GeForce 4 with a 5(ish) years old PCI Diamond Viper SE. Still crashes ->
it's not videocard that's causing it!. (NOTE that it took about 1 hour with PCI card before it crashed for the first time).[/li]
[li]Luckily my mobo supports DDR and SD RAM, so I disconnect my DDR module and plug in two SD modules (taken out from a perfectly working PC running XP). Again, this doesn't help ->
it's not RAM's fault.[/li]
[li]The two things left are Mobo+CPU and HDD. I really don't think it's HDD.[/li]
[li]Conclusion - It must be motherboard or cpu.[/li]
[/ol]
I remember reading something about winXP driver(!) for Athlon XP cpu's, but I cannot find it anywhere on the web. If someone knows where it is, please post a link here.
Or, this could be damaged motherboard (which explains my case - all this started after some improper handling of my PC by Austrian Airlines

).
The only thing that goes against this conclusion is the fact that this doesn't seem to happen under other OS'es. I will try reinstalling XP tonight, I'll tell you if it helps.
It would really help if people tried carrying out a similar elimination procedure and posted results here..