I have the same problem... I had the free edition of avast about 1 year. And couple days ago, i have fond a licence on torrents
and after the update to 5.1 version, my antivirus stays more time disable (by me), than active... I can`t listen music, or watching a movie... All goes in frames and is very annoying! I put on exception list my torrent, my winamp etc. i even try every option one by one to see wich is going bad, but nothing... just disable antivirus works.
I think i`m going back to free edition.
PS: Excuse me for my bad english!