I have read with interest through the possible issues of corrupt data and know that during the session where my problem must have occured I had been "cutting & pasting" from Genes Reunited and Generations. I was ultimately forced to close my GR session as I tried to open a members tree containing 55,000 relations. After 30 minutes of "Not Responding" my poor old stable XP laptop needed help.
I'm not suggesting GR are at fault but that this tends to support the Drivers etc. as the cause.
Alternatively, could "cut & paste" have something to do with corrupting a record in some way? I wasn't pasting anything into the area of the corrupted records.