Missing Files

I just bought the WinSE upgrade and attempted to install it. The system is working fine, so I thought. When Windows was ready to copy the files for the upgrade I got a message saying that it can’t do the upgrade because of missing files necessary to do it. How can I find out what files are necessary for the upgrade to go in. Can I load these files from the Win98 CD??
I really don’t want to start from scratch and load Win98 then SE.

Regards,

Frustrated…..