Kt6v system problems

Question

I have a system based on a MSI KT6V board and i'm currently experiencing problems with it. The system reboots once in a while, and the event viewer shows the following error:
Error code 100000be, parameter1 f0b4ff08, parameter2 0ea5b121, parameter3 eb6c2a40, parameter4 0000000b.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
This morning when i turned it on it wouldn't load windows until the third reboot saying that a file was corrupt or missing from the windows install. I want to mention that the windows was cleanly installed 1 month ago, and the computer has only been running office software.
The specs are:
MSI KT6V
2 x 512 PMI DDR (brand new checked with Memtest86)
AMD Athlon XP 2600+
WD 36 GB raptor SATA
560W Thermaltake Pure Power PSU
Thanks

Answer 1

The system is more than three months old. I did the reinstall about two months later since i wanted to have a clean install with service pack 2 included in the install cd, rather than upgrading the existing windows copy (did it and i had some troubles with the SMC Wireless Network adapter in it).
Basicly my first guess was the memory... During the two months i had one DDR 400 AM1 module (512 MB) loaded.  Before the OS reinstall i bought 3 more PMI modules (DDR 400 512 MB). First i loaded one PMI with the AM1, but that gave some errors (memtest86 clearly showed them). I removed the AM1 module and put two identical PMI modules. The two modules i used were previously tested on another system (AMD Athlon XP 2000+ with Msi Kt4v) and they showed absolutely no errors (used the sytem for 3 days, no problems whatsoever, memtest showed everything ok). I also ran memtest on the system with which i have problems now, again everything was the same.
Another thing which change was the PSU, from a no-name one to a Thermaltake 560 W one.  I didn't really trust the noname PSU and considered it was the cause.
Till yesterday the modules were ran at DDR 400, now i changed it to 333 as suggested in a previous reply. Will see the results tomorrow.