Premiere Pro CS4: no sound after importing converted file/ no sound after copying edited file from other project

Hi

I've got two problems with Premiere CS4 (I'm working on a pc).

1) I converted a movie in with .MOD extension using AVS4YOU in a file with a .MOV extension (exported to default settings: QuickTime HD quality 480 p-(H264,848x480; MP2/4(AAC),320kbps)). The converted video works perfectly in QuickTime, but once imported in Premiere, the sound disappears (image is fine). I tried to export the files to other settings, but nothing works.

2) We edited some clips in another Premiere project. Now we want to import those edited clips in our final project. We tried copy/paste, which works fine until we save and close our final project. If we reopen it again, the sound of the copied clips is gone.
We could export the edited clips, and than import that movie in the final project, but you'll notice the loss of quality.

Any ideas?

Thanx!