I had this problem a while back on my d2. What I did was unmout the sd card, turn off the phone, pull the battery, pull the sd card, reinsert the sd, reinsert the batt, restart the phone. That worked for me but it didn't recover the images that were broken in the first place it just stopped it from happening again.
With face finder on, it focused on two subjects in a large group. When I pressed the shutter icon, flash went into a strobe mode. Only way to turn it off was to turn off the DX.
Note to self... Turn off face finder for large group photo.
It appears to be a Froyo bug. It is a subject of discussion on Motorolo's Droid X forum, although they do not appear to have acknowledged the issue. You might want to go and add your two cents to the push to have them do so.
It is apparent that a number of folks are having this issue, and for many the photos are summarily deleted by the device shortly after the issue crops up.
I can take bugs, but start deleting my personal data, photos, ect., you got a problem.
If it was Apple's iPhone doing this, the lawyers would already be in a feeding frenzy.