Deleting or clearing cell(s) crashes Excel

I have an Excel 2007 workbook about eight megabytes in size that has started
crashing Excel whenever I try to delete a cell value or clear the value or
cell format using the Clear command from the ribbon command button. I've
tried removing all add-ins, but the problem persists. I end up staring at
the spinning blue circle hoping the Not Responding message will go away, but
it doesn't. Does any body have any idea what's going on here and how I might
fix the problem?

Ken