After doing some research I found that Win 7 does not like the starforce program and other people have bought the starforce free edition. I did find the following post by supposetobeworking who got win 7 to work by removing starforce in a little different way from the post in this forum (
How to play Silent Hunter III without the DVD in the DVD Drive (Starforce free) and included a ubisoft link.
http://www.subsim.com/radioroom/showpost.php?p=1342244&postcount=92
If this does not work post the error message you are getting.
Good luck
If youhave to uninstall sh3, get one of the several free registry cleaners available at download.com and clean your registry. It might be a problem that is left over from the original installation in the registry causing an issue. Anything like CC Cleaner, TweakNow RegCleaner 2011 , Ect. should work. Just an after thought.