Windows 7: Incorrect time - again!

I know this has been posted about before, but I'm confused again.
After British Summer Time kicked in on Sunday, Windows say it went forward 1 hour, but it didn't.
If I sync the time, it is OK, but when I booted into OS X (dual-boot setup) it sets the time correctly, then going back into Windows 7, the clock is behind an hour again.
I then noticed that my BIOS time was behind an hour as it didn't move for BST, so I reset that.
What is going on? What role does the BIOS time have in all this?
Also, I seem to recall that I put in some registry edit about UniversalTime previously.
Don't know what effect that has on all this.

Just had another thread with the same problem and British Time. It would be my hunch that the British Time change is not programmed correctly. If that is the case it may be best to wait until MS has enough complaints and sends an update.

Fair enough, but do you know how reliant Windows 7 is on the BIOS time and date?

I've started having a similar problem, but on US Central time, not BST. Instead of jumping a hour ahead, mine is jumping 5 ahead. It is not anything to do with the BIOS time, because that remains correct. I don't think that it has anything to do with the CMOS battery, because if that was too low, the time would fall behind, rather than ahead.

It seems that it is always only the hour that gets wrong, because the minutes and seconds are right on target. I changed the time server again, just in case the one that I was using went haywire, but I seriously doubt that is the case. It seems to me that it is something in the OS itself that is not right.

EDIT: Considering the difference between BST and US Central DST versus UTC, it seems that the OS is trying to run on the latter, rather than the zone on which it is set.

Strange. I've had no problem with mine. Switched my system off on Saturday evening when it was still GMT here in the UK. Switched on again Sunday morning, and the time was showing correctly as BST.

Incidentally, all time servers work to UTC. This is why you can choose any of them and still have the correct time. Your computer uses this time value and then adds or subtracts the appropriate number of hours and/or minutes from that value according to your time zone settings. If Daylight Saving Time is enabled, then between the appropriate dates and times an hour is added to your time.

This effectively is as follows, (Zone diff can be +/-):

Standard Time: UTC + Zone diff

Daylight Saving Time: UTC + Zone diff + 1hr

u runnng out of battery?

If you're running on Apple hardware, this is a problem almost all Windows on Apple users have. I have it as well, although in a different respect. My time will randomly switch ahead 4 hours without notice. I think it has something to do with the way that Apple's BIOS is set. Apparently it sets time in a different manner than normal Bios does. The reason Windows is effected while OS X isn't is because OS X is made to read time from Apple's SMC/BIOS format. The only solution I've found is to install Boot Camp 3.1, that usually fixes the problem.

I've also had an issue with the time change. Using linux it updated by adding 1 hour no problem. Windows ended up adding 2. Never had this issue before. Strange...

While I have had this problem on my primary computer, my secondary has not missed or jumped a lick. This seems to indicate either a hardware or software difference between them. I have intended to compare Windows Updates between them to see if anything time related is different, but have not gotten around to it yet.

EDIT: I just ran through the updates and found several differences, but none that would relate to this time issue.

Guys, I remember from an old post how I solved this problem.
Try adding the following DWORD to the registry and set the value to 1.
Code:
HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversal
Don’t forget the value change to 1 then reboot.
I had forgotten to apply that after I re-installed Windows 7.
All is OK in my Time world now!