Requesting help PLEASE- year constantly changes on my Shuttle SB65G2!

I have a Shuttle SB65G2 pc, and I have had a problem with the year
changing for quite some time now and am out of ideas. What happens is,
several times a day, every day, while in windows, the year changes from
2006 to 6006. When I enter the BIOS, the date is correct; it does not
change; this only happens in windows. It does it randomly and is
driving me nuts at this point. I've got (2) 200gb hard drives
installed, 2gb of memory (but it happened when I had 512mb and 1gb of
memory too), WXP sp2, office 2003, Forte Agent, all updates; nothing
really out of the ordinary installed- ms money, roxio to burn cds/dvds,
nero, some labeler programs, etc.. Here is what I've tried to fix
it:

Upgraded the BIOS to the latest version. (not remembering exactly when
this started, I thought maybe it's a problem with the latest BIOS
version, so I got all the BIOS revisions from the manufacturers
website, and went back down a few revisions, then all the way back to
the original BIOS revision, and the problem remains)
Installed a brand new cmos battery
Completely wiped out and re-formatted my hard drive and reinstalled
everything from scratch.

Again, it's ONLY the year that changes and it's always from 2006 to
6006. The day, time, and day of the week never change only the year.

I'm hoping to find some answers because every time this happens it
makes my computer go nuts due to date sensitive programs like outlook,
Norton anti-virus, etc..

A hugh TIA to anyone who may be able to shed some light on this issue.

feel free to contact me at
m c d e i g o < at > h o t m a i l < d o t > c o m