Amy,
Apart from viewing your music files on Limewire, are your folders on your computer showing this change from mp3 to exe? I never view music info THROUGH Limewire. I always view file info on the computer ONLY. So, the question I have for you is:
Are your mp3 COMPUTER files being changed to exe? Or just your Limewire mp3 files?
I'm assuming your answer is the computer files are being changed, based on the info you have provided.
Did your music files vanish from your Limewire program AND your computer file folders?
This is clearly a lesson in file backup. We need to realize the danger in NOT backing up our files, just in case.