What sort of files wont open...Where they MP3 and have now turned into zip files ??
Even if they haven't listen to the security warning and get rid of them...
Scan your computer with your AV and spyware apps to be sure...
AVG is a good one for getting rid of the virus that turns Mp3's into zip files...
http://free.grisoft.com/doc/2/lng/us/tpl/v5