XP Pro System Lock's Up Constantly?!?!

[Wade]

I am having another issue with my system.
The system constantly locks up? (Freezes and have to
reset to reboot)
I have un-installed Q811493 and fixed my sluggishness,
however I have had, and are still having the lock up
issue on this machine!
The computer will lock up at random, it can go for hours
sometimes or lately (within the last 2 weeks) it crashes
after only a few minutes of being turned on?
It will crash at the desktop if idle, during default Win
screensaver, it will crash in applications, games,
internet, whatever?

This has only started to occur within the last 30 or so
days?

I have systematically replaced every piece of hardware,
short of the HDD, MO-BO and CPU, in the machine as I have
lots of extra parts, and it still crashes?
I have rolled back drivers for all hardware to earlier
known stable ones but still the crash?

I was wondering if there are any other issues with any
more of the "Updates/Hot Fixes" that anyone is aware of?
Short of removing them all, I was hoping someone might
have an idea...
I have seen several other posts on the MS newsgroup with
the same issue, however no response to correct yet?

System Spec's:(system is 1 year old)

Windows XP Pro
NAV 2002 - updated weekly
Abit VH II MO-BO W/Via chipset
Intel Pentium III, ~1000MHz (not over clocked)
512MB Crucial PC 133 RAM
Western Digital 80 GB 7200 rpm Ultra ATA 100
nVidia GeForce 4 TI 4600 (4.3.4.5 nVidia driver)
Sound Blaster Live. (latest driver)
3Com NIC Card
Logitech optical mouse and standard keyboard
DirectX Version: DirectX 9.0a

Please Help!!!