Eudora
When AD has indexed Eudora's mailboxes and you compact the .mbx files the indices will be askew.
Updating the indices solves the problem like totally, dude.

Certain binary files
When a query html output incorporates an entry for binary files, some binary files contain characters that will cause AD to muck up the table entry a bit. (I've seen it happen with bootsector files like made with linux' dd) It will not hamper displaying the rest of the query results.