I had serious data issues lately.
Incident 1: On Wednesday I packed my bags and iPod just before I went on short sailing vacations. I added one great song to music and podcast packed iPod. I planned a lot of relaxing and iPod was important part. Only on Hvar I realized that I messed up my last sync with iPod and the only song I had on it was the last one. Mini disaster.
What I learned: Do not ever use two iPod managers at the same time. Especially not iTunes and ml_iPod.
Incident 2: When I came back my brand new 200 GB WD hard drive died. Died as in dead. Not working. Disk volume name was Data, so you can image what I lost. 10+ years of email, 2 years of photos, my documents, Mojca's documents, sources to some of my projects. I have some backups but they are outdated and not complete. Major disaster.
What I learned: Backup. If you buy a DVD writer, use it to burn backups, stupid.