How can i get these programs to install again?

[crd65]

Basicly when i first bought my which was a few yrs back, i installed programs such as Itunes , SuperAntiSpyware , Nero , etc.
Recently these programs have all gone messed up and i am unable to use them, so i uninstalled them all, and then tryed to reinstall them , but halfway through the install a popup will come up saying C/:Common-files has something wrong with it and when i click X on the popup the download bar rolls back and stops installing.
PLEASE can someone tell me how to fix this.

[TERRENCE A]

what is wrong is your registry. try eusing free reg cleaner. this will clear any traces of the old programs.