Well, both my desktop and laptop do this. These are both modern machines (both are less than a year old). The clock auto-update and firewall have NOTHING at all to do with this.
EVERY computer I've had in the last 10 to 12 years (or more) was able to keep the correct time no matter what operating system was installed... even DOS. Powered Off or On... I rarely, if ever, had to update my time. Over this time, I've had only one machine that needed a replacement battery.
Any Windows machine should be able to keep the correct time even with the auto update disabled. Actually, to be correct, Windows shouldn't have anything to do with this, but it does. It has to, as usual, screw with everything.
My machines lose anywhere from 5 to 40 minutes each day. We've been performing a variety of experiments on this exact problem. We tried each machine with updating on, updating off, and also with no internet access at all.
We've had access over the last 3 months to the following machines: an Intel P2-400MHz, a P3-550MHz, a P4-2.6GHz, three older AMD machines, a NEW Core 2 Duo notebook, an AMD Athlon 64 X2 4600, and an AMD Athlon 64 3400(?) mobile.
Well, we couldn't get Vista installed on all of those.
The bottom line is that with 98, 98SE, 2000, or XP, NONE of these machines had any problem keeping the correct time. (for XP, we used SP2 in all cases except once. For that, we used the P4 machine and installed XP with no service packs).
With Windows ME and XP Media Center, we had issues with the auto-update working at all. And Media Center, out-of-the box, updates daily instead of weekly. Even so, neither slowly lost minutes each day.
With Vista (tried the "trial" HOME PREMIUM and ULTIMATE installs) installed -- starting with the P4-2.6GHz machine and up -- we had lost minutes on EVERY machine!
With VISTA, we lose minutes EVERY DAY!
With DOS through XP, we don't!
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