No sound for certain files

When I insert certain files that I have recorded from several CDs they insert
ok but when I click play there is no sound. In the preview I can see that
the track is playing but no sound. This problem originated after I installed
the XP service pack 2. It seems to be just files that I had before the
service pack. I tried to delete the files completely from my hard drive and
re-record them using Media player but it did not work. I purchased the
intervideo mp3 decoder for Media Player and recorded them in a different
format and it still did not work. Could it possiby be the location that the
files are being saved to? I have read FAQs until I am cross-eyed and have
spent way too many hours trying to figure this out! I ran the fix program
and just about everything else. Please help!