system date changes after restart

[Spectrum]

Both systems I am working with have the Asus P4P800-E Deluxe Motheroard. Both were upgraded to SP2 recently. Went back to SP1 on one but it still does the date swap. Thinking it must be some compatibility issue between the board and SP2 though i don't pretend to understand how. Have to pursue it with Asus I guess. Off on holidays for a week though so it will have to wait until I return. Thank you everyone for the suggestions though!

[Podge]

This is my system, let me know if there is anything else you need to know. I have flashed the BIOS and done other stuff via MSI Website and their Live Update facility. The date still changes, don't know what it's going to do when it reaches the 13th October, if it twists that date around it will be the 10th of the 13th, it'll have to invent a new month!

Operating System System Model
Windows XP Home Edition Service Pack 2 (build 2600) No details available
Processor a Main Circuit Board b
1.80 gigahertz AMD Athlon XP
128 kilobyte primary memory cache
256 kilobyte secondary memory cache Board: MICRO-STAR INTERNATIONAL CO., LTD MS-6570 NVIDIA nFORCE K7N2G-L
Bus Clock: 133 megahertz
BIOS: Phoenix Technologies, LTD 6.00 PG 08/02/2004
Drives Memory Modules c,d
123.51 Gigabytes Usable Hard Drive Capacity
65.88 Gigabytes Hard Drive Free Space

IOMEGA ZIPCD1024INT-A [CD-ROM drive]
LITE-ON DVDRW LDW-811S [CD-ROM drive]
3.5" format removeable media [Floppy drive]

HDS722512VLAT20 [Hard drive] (123.52 GB) -- drive 0, s/n VNR3GEC3G49ELK, rev V33OA60A, SMART Status: Healthy 480 Megabytes Installed Memory

Slot 'A0' has 256 MB
Slot 'A1' is Empty
Slot 'A2' has 256 MB
Local Drive Volumes

c: (on drive 0) 123.51 GB 65.88 GB free

[Podge]

Latest News:

I went into BIOS upon start up and changed the date to 13th October 2004 to see what would happen (there isn't a 13th month so wanted to know what it did). When XP loaded the date hadn't changed and was showing 13th October 2004.

Re-started again and changed the date in BIOS back to today's date, 11th October 2004. I was fully expecting it change to 10th November 2004 but it showed the correct date on the desktop. Don't know if this has fixed it or not. I'm getting fed up of re-starting my PC though!