Quicktime 7.4.5 on Tiger stopped playing audio in .mpg and .mpeg files

The other day Quicktime studdered on an mpeg file and finally stopped playing the audio on all mpeg files, video still plays find but no audio, VLC plays these fine. The problem is now that this has happened some of my games (like the one me and my wife were playing which was Mystery Case Files: Madame Fate) also stopped playing audio in the game, there are a few others too. I am assuming these games use Quicktime and some type of .mpeg codec to for their sound. I have totally deleted QT and reinstalled, i have run Applejack from single user mode to run disk utility, repair permissions etc and i have reinstalled Mac OS X Tiger "over" my existing setup. I also have the $20.00 mpeg-2 file from Apple installed, none of this works. Any help would be so appreciated!! The only other option is to completly reinstall my system to factory settings 😟