http://www.theinquirer.net/gb/inquirer/news/2008/11/13/avg-update-cripples-windows-xp

"ANTI-VIRUS software AVG8 has got it into its head that an important Windows XP system file is a Trojan.

The software deletes the file leaving punters with a Windows XP that endlessly reboots or is unable to reboot at all. Still it is highly effective as an anti-virus technique. Try getting a Trojan to do its nefarious work under those circumstances."

This was so funny I had to post it.  AVG has been notorious for glitchy programming, but when it starts mistaking Windows system files for trojans, you've got a problem.  Luckily, people running the program under English Windows does not have to worry about this particular problem, since it only effects OS from other languages.

I remember when I was looking for an antivirus, I was about to download AVG, but decided that the process was too complicated and downloaded avast! instead. Luckily, because I have a spanish-language OS.

That sucks, though, I'd be seriously pissed if that had happened to me

If anything, vista is a virus.

its a weird bug, I prefer AVG over most anti-virus programs. I just wont be updating AVG for a while.

If it happens then boot into DOS using a startup disk and copy the file back from your CD. You can also copy the deleted file to your floppy and then boot into DOS and copy over. Either way, DOS is your friend.