When I left my last job, I made a backup DVD containing all my personal stuff that had been on my work computer. Bookmarks, email archives, documents, things of that nature.
I came to retrieve something from the backup today only to find that whilst it looks as though the files are there, and of the right size, they are in fact corrupt. Each file contains nothing but zeros. Huzzah.
Gah, I hope to god that the three DVDs of mp3s I backed up have been similarly effected.