I'm pretty good with registry's, but I had one program that gave me the same problem as hooch. I deleted every key and folder this program put on my computer. I even uninstalled and ran a registry cleaner and I reinstalled and the damn thing still knew that I had installed it before! So I went to a warez site and got a freaking registration code for it and now it don't seem to have any problems
and if that doesn't work do a search on http://www.google.com for the program name and the keywords "serial", "crack", or "hack". If the normal web page doesn't work, use the same keywords and click on the "groups" option to hit usenet - you will usually find what you need...