"Cannot empty clipboard" - cut and paste problems

There is a user in our departmenr that regularly copies data from a non microsoft program to excel 2003. By choosing Copy All in Business Objects, he usually has no problems in copying and pasting the data to Excel. But, atleast once or twice a week the copy and paste function stop working, the Paste will be grayed out if he right clicks in Excel, and ctrl v doesnt work either and she has to restart her computer, which is obviously a frustration and waste of time. I checked at his computer and went to Edit >> Office Clipboard, but the error "Cannot empty clipboard" came up. After closing Excel and Business Objects and restarting them, nothing helps as well. Any ideas?

I got the issue due to virus. The clipboard was corrupted and copy paste was not working. For temporary basis I installed a third party clipboard software that worked fine. Later on re-installed Microsoft Office things went back to fine. There is no issue rightnow. So you have to just re-install Office back from scratch and then check back. I am sure it will work properly.