It sounds like the uninstall file for the intended app(s) are missing. Either you removed/deleted the program directory without going through add/remove or the file was never put there in the first place on install. If the directory for the app still exists look for files called either uninstall, unwise or something similar regarding removal. execute the file manually from there.
If the file/program doesnt exist anymore you can try the registry if you feel comfortable with it. Other wise try reinstalling the app or finding the uninstall file that goes with it either from the CD or whereever it was installed from. The latter of the 2 are your safest bets if you havent played with registry before. Once you done one of the 2 you should be able to remove it properly from add/remove in control panel. If replacing/reinstalling the file doesnt work then you will have to do things manually and use the registry to clear it out as the other answer said.
Jason