A friend of mine said that he was scanning his computer for viruses and restarted it after it was finished. As he was trying to log back in, it asks for windows to be activated. Keep in mind though that it is the OS that came with the computer and it says that the key on the side of the computer is not valid. We booted it in safe mode and it let us log in just fine. Also the message number that it gave us (message number 45090) did not show up anywhere while searching for it on the net for what it means. Any help would be greatly appreciated.

C_Esq, dunno just why or what, but my gut says the AV deleted the validation cookie. Perhaps list it as an exception? Some AVs save a log file and you can restore from there. Yours? Another 'maybe' (dunno if it'll work) is to restore to a time pre-scan. HTH. Ed in Texas.