Yeah, it's crazy how music vanishes. Well anything really, from the internet, since keeping it up needs active work on someone's part.

I too have a library that's somewhat in disrepair. In my case, a corruption happened when I was hauling my hard drive around - and it didn't happen when I chucked the hdd in my bag, it happened when I have set up the wrong sector and header information in my buddy's bios! Suddenly the chemical brothers songs had some black metal in them.