well for scuba... another problem which im thinking about is smetimes temp files prevent the install. it's happened to me. If your on Windows XP go to
C:/Documents and Settings/(Your user account)/Local Settings/Temp
(your user account) means select your account name
i.e. C:/Documents and Settings/BigBrownPimpsta/Local Settings/Temp
delete all files possible in this folder
and local settings is a hidden folder so u have to enable it in the folder options in control panel
and another solution for both of you use the drivercleaner available @
http://www.driverheaven.net/cleaner/
ill see wut else i can do wit dis problem