Updating IE from a previous version

I have run into this problem a lot and haven’t really gotten an answer that helps me from Microsoft.
When trying to update alot of computers from IE4, IE4.01, or IE5x to the latest version (IE5.5 SP1) I seem to run into the following error on abouta dozen PC’s I’ve visited.
“A PREVIOUS PROGRAM INSTALLATION WAS NEVER COMPLETED. YOU NEED TO RESTART YOUR COMPUTER TO COMPLETE THAT INSTALLATION BEFORE RUNNING INTERNET EXPLORER SETUP. SETUP WILL NOW CLOSE.”
Doesn’t matter if you restart your PC a100 times, you still get the same message everytime you try running IE5SETUP.
Again, any help I found from Microsoft has NOT been helpful AT ALL!!!
Will very much appreciate if someone has a real fix for this. Thanks!