Ok, thank you guys. Some further news:
1.) I think I found out the solution to the
initial problem why I created this thread.
My girlfriend had told me (over the phone) that the time was increasingly off during the week. The first thing I thought of was an empty cmos battery. So now I'm here and found out, that the time was indeed off (I think it was 18 hours) but the minutes were correct
So it can't be the battery.
Anyway, It comes from the freezing because during every windows boot, windows recognizes that is supposedly hasn't been booted during the winter time and changes the time one hour back. So windows has been booted 18 times since last sunday :lol: An unfreeze, boot, and refreeze will fix the problem I hope. Sadly I can't test it, because I don't remember the password and my gf isn't reachable for the next few hours.
2.) Unfreezing doesn't change the Admin issue. I've tried that already in the past. I just didn't have enough time to bother with it (about a year back) and just changed the time in BIOS.
3.) The tool used for freezing is
http://www.faronics.com/enterprise/deep-freeze/
4.) I enabled the admin account in windows (that is usually hidden) and also there I can not change anything (concerning time). Also, under my impressionn, the freeze tool doesn't forbid anything. You can do what ever you want, but after you reboot, partition C is recreated, even deleted files are back there.