Missing Quicktime Plug-Ins

Hi,

I've been trying to edit videos in iMovie but have been having issues with the audio. Any time I try to play the clip in the editor it stalls and I have to force quit because iMovie stops responding. If I delete the audio from the clip it plays fine.

I've tried: 1) saving the library to a new place by holding down option at the open; 2) deleting all the iMovie settings by holding down command/option at the open; 3) I redownloaded iMovie; 4) I tried converting the videos into a different format by exporting them; 5) I updated all software and apps. Nothing has worked.

I believe it is a Quicktime issue. All of the Quicktime plugins seem to be missing. There's no folder under /Library/Quicktime or ~/Library/Quicktime and the folder ~/Library/Internet Plug-Ins shows up but there's nothing in it.

I regularly delete files to maintain the memory storage on my iMac so it could be they got trashed in one of those deletions.

I'm wondering if there is a simple way to restore these plugins or if anyone has ideas if the iMovie issue could be something else.

Thanks!