I had to uninstall my office 2003 and when i went to reinstall it on the same computer it keeps saying that the product key is invalid. What can I do to correct this?

I have the same problem, too! It would be great if someone could help us out. Thanks!

Call Microsoft support. If they believe it's valid they will give you a new key.

This is caused by a report being filed by someone that had a corporate license pirated...Microsoft de-validated a lot of these corporate licenses that was suspected of being pirated with a fix.
The only way is to do as SNM suggested and contact Microsoft for a new key. You will have to have to prove that your version was not one of the pirated versions though! Good luck on that.