Hi Stief,
I think you fixed it!! I went to the Control Panel,"File Exchange",scrolled down to ".mp3", hit the "change" , went to QuickTimePlayer to Mp3, hit "change". I also changed some mpeg. The files I changed looked like AppleWorks (you know, the page with the dog ear) with ???? after it.
Anyway, I haven't had any trouble since.

Thanks again -- I never knew what File Exchange was!