If you know the name of the program you're after, why not just search for it on google, or WinMX?
Also, use a bit of ingenuity regarding the program you want to use. As IanC said a minute ago, and you totally ignored him, there is probably a free program to do the job you want without having to resort to any dodgy registry editing or patching.
Finally, if all that doesn't work, try VoidMain;s solution above, his remedies almost always work perfectly.