excel 2003 slowing down
 

Hi any suggestions as to what could be causing the following in excel 2003,
it has just started happening. Everything was OK until this morning and I
have done nothing to the computer

Whenever I cut it takes ages before I can paste I just get a egg timer for
up to 20 seconds
if I fill down or across again it takes ages before anything happens.
also if I undo anything again it takes seconds before anything happens. As I
said at the beginning it has just started happening after over a year with
no problems.
Thanks Ron