I bumped into this way way way back when after installing a tape drive on a server.
You did that off the original disks, which of course didn't include the fixes and promptly overwrote the new dlls etc.
Better version control and an increase in modularity for online updates seems to have got rid of these issues.
As we all know though MS still drop the odd ball on this front, at least now it's an exception.
I'm glad those days are gone, hands up who has successfully un-installed a service pack?
Always a nuke and re-install situation that after my first lesson in why gullible is bad.
:D