Day/Date Keeps Changing on Reboot in XP and BIOS

Any assistance much appreciated with this annoying problem.

Whenever I reboot (soft or hard) Windows XP within the first 1-12 days of the month, the day and month are swapped.
It's really annoying as the file save data, Outlook messages etc are corrupted.

e.g. today is the 11th October about 16:00. When i rebooted the date had changed to 10th November and also the time had changed to 17:00

If the date is between the 13th - 31st of the month then the reboot is fine.

When i go to the BIOS that is also incorrect (after originally being correct).
I can correct the date in BIOS or XP or both and it does the same next time.

I have:
Checked the BIOS correct.
Loaded the updated BIOS for my motherboard.
Changed all references to the same European date format.
Checked language, location, settings.
Looked in the BIOS for day/date/time format (the BIOS uses words for the day and month so cannot be muddled up).
Selected GMT as my time zone.
Renewed the motherboard battery.
Checked the back-up battery voltage.

I searched in vain on the internet and Windows help. Those problems aren't the same as this and seem to revert to BIOS battery problems which is fine, as far as i can tell.

What is initiating the change?

Also bugging me: why doesn't the system which is initiating the change give me an error between 13th-31st of the month when it presumably tries and fails to change to the 13th-31st month? That would help me track down the problem.

More information:
There are 2 users registered on the PC. Myself as the administrator and my girlfriend as a user. When I log in the date is changed and incorrect. If i swap to my girlfriends profile the date is ok, then when i swap back to mine the date is correct! What the hey?!?!

Any ideas what is going on?

many thanks
mick

 

Here is the key I think. The fact that it only effects one user indicates that it is a problem associated with that user's profile (as opposed to something like a CMOS battery failing). Check your regional settings in Control Panel. I think you will find these are different for you and the other user. Set yours to match the other user's.

 

Reggie. Thanks for the reply and suggestion. I have checked the different settings and can find no differences anywhere in control panel. After months (literally) of looking and testing i have got nowhere.

To make matters more complicated i have just found out that the effect still applies if i log on as the girlfriend first then swap user and swap back again (opposite to what i said in the first message). So it affects the first log on profile not any one profile in particular. This makes me think it isn't in the local profile settings.

The system must be calling for information or formatting from somewhere. Any more ideas?

thanks
mick