original installation source

Hello!

I am trying to install Microsoft Office Professional Edition 2003 to my labtop but it keeps telling me to give the original installation source and the installation disc is in the computer so I don’t understand why it isn’t working. It keeps saying “a required installation file P2561407.CAB could not be found” and “if you installed Microsoft Office Professional Edition 2003 from a CD, please insert your CD” but the CD is already inserted.

Please Help!

Thank you!