When you attempt to install a new network service on an upgraded SBS 4.5 computer, you receive:
Noncritical Error                               An error has occurred.                               Unable to open the file path and file name.                               A non-critical error has occurred. You may retry the operation, ignore it, or exit the entire Setup operation.
If you retry, it fails. If you skip, you get the same error on another file.

You are most likely to receive these messages while installing WINS, DHCP, or RAS.

The SBS 4.5 upgrade CD-ROM does not contain the required files. Use CD-ROM 1 from SBS 4.0. After the install, reapply your latest Service Pack.

NOTE: The SBS 4.5 upgrade CD-ROM contains SP4 - <CD-ROM:>\Bkoffice\I386\Sp4setup.exe.