I made a grid of all items containing a reference to a file in the FileRef fields, with FileName, FilePath, and FullFileName as columns (thought it would be interesting and might be useful).  I used FileName as the grid source.  There were 1342 items with an entry in the FileName field.  After a crash, I discovered that only 403 items still had anything in the FileName field (the FilePath field still contained data).  IQ crashed a couple of times before I confirmed the data loss.  So I'm wondering if IQ has a problem with using FileName as a grid source, or whether the crash was unrelated to that.  But I thought I'd let you know.  Of course I have a backup I have not really lost any data.

 

Or maybe somehow the filename format had something to do with the crash?  Here is the "before" picture of an Item where the FileName field text got deleted: