Unable to Loan MS Office Pro 2000

Have full version of MS Office Pro 2000. System running under Win98SE.
This is a fully registered version of the software.
During the initial part of running the both a) the runtime install and b) a manual execution of the setup from the CD I received the following message:

Header Block: Windows Installer
“This patch package could not be opened. Verify that the patch package exists and that you can access it or contact the application vendor to verify that this is a valid windows installer patch package.”

I was able to install Disk 2 of this sofware without this message.

What do I need to do to solve this problem?