I had a issue earlier this week where 2 different records showed up as all of the fields with a ? in them, and you can't edit them. I researched, tried to find the problem, talked to the people who had used those records, nothing apparently out of normal.
I restored the records by importing the two records from a backup from the previous day. This morning, we discovered they have appeared again, and upon deleting them, they reappear?!