I've had several problems of this sort. In three cases they were hard drive failures. Another case I loaned out a hard drive to someone who's system did something nasty to the file allocation table, such as telling it the drive was a different format! This was totally saved by using a Linux (Knoppix) system-on-a-CD which restored the correct setting to the table. This worked slick.

I had a trickier problem which is similar to the ones mentioned here: I was running windows XP Pro on a 160 GB single partitian hard drive. Something blipped in XP and it wouldn't boot. I used the XP Pro CD install to get it running again but of the 20 GB of music material that was there, I can only see about 4. When I look at the Properties window, it tells me that 20 GB of the drive is utilized, but the file system can only ever see the 4 GB plus the operating system. I think when I reinstalled XP Pro I did something to zap the file allocation table or the directory, but I'm convinced I should be able to recover the unseen 16 GB of music. I'm trying to learn linux enough to do this, but in the meantime I have a large Hard Drive I can't write on.

I've had some other problems which are more PC related and not worth going in to here. But I've learned not to play favorites. Windows, Mac, Linux, each have their strengths and weaknesses. Never trust a single copy of anything, and have a 'system' of backing up. There is NO single panacea.