Upgrade fails w/product catalog fatal error

Please help me if you know about this issue. I tried to
be brief.
What I did:
Windows pro 2000 chose upgrade performed from installable
(not upgrade CD)

Problem: may not have used the original cd key from
manufact. Had sveral CD keys given to me from manuf. used
the last one he gave me.
ERROR:
fatal error looking for file "NT5INF.CAT" Product Catalog
Enter directory
OK Cancel
Nothing I did Could not find the file using C:\ D:\ *.*
etc. but could not use explore because the
System is now down, restarting system restarts install
and the above error repeats.
Thanks to any who respond and God Bless YOU!
ruthie