Excel copies graphics from one sheet to another arbitrarily
 

This is the second time this has happened so I'm wondering if this is
known to anyone.

The sheet is about 6MB, light on graphics, very heavy on VLOOKUPS and
INDEXs.

The first time, I didn't know how it happened. Just noticed it one
day.

This time, I had just dragged down (copy down) a 4 cell row of
formulas down about 20,000 rows.

It did a calc and froze for a few seconds, then came back seeminly
fine with the exception that the graphics in sheet 8 were copied to
sheet 9. In the same position.

What the heck?

Anyone seen this kind of behaviour before? It puts me in such doubt
of Excel's integrity.