Half the files corrupt……

Using WinXP Pro w/updates

My “B” machine has a WD 80GB primary drive and a WD 40GB slave drive I use for storage only.

A couple weeks ago I discovered that about 1/2 the files on the slave drive didn’t work. True for all types of files; DOC, JPG, GIF, RTF, MIDI, etc. I can go to any folder or sub-folder and about half the files are no good.

How can half the files in any given folder be good, while the other half are corrupt and unrecoverable?

Lost a lot of pictures, but still, some of the pictures are just file.

Never heard nor read of anything like this. Does anyone have any idea what might have happened? If I had some idea of what happened, I could take steps to prevent it from happening again.

Thank you.