I’ve renewed my key, but no matter what I do when I try to enter the key, it tells me it’s invalid. I know there’s no extra spaces or anything and that I’m getting the entire key. I don’t know what to do.
Have you simply tried the method of copy and paste?
Besides some registration problems were solved in pre-release of avast system update http://forum.avast.com/index.php?topic=34612.0
Is your system time and date correct?