Hi there, I am having the same problem. I've been working on a spreadsheet and sometimes need to copy the content from one cell to another cell (on the same spreadsheet). When I do this, I get that spinning ball and have to force quit. Sometimes it works, but most of the time it doesn't.
I am using Excel 2008 in Leopard (10.5.8) on an Intel Mac. I select the cell, hit command C, then select another sell, and hit command V. This is not a formula, just a straight copy and paste. I have tried rebooting and also repairing permissions, but neither has helped.
Any idea of what might be happening and how to fix?