Re-install the cam software again, if everything works properly after that then fine, if not then un-install it again using ...
during the un-install (if you need to do that again), when you are asked if you want to re-start your pc now, decline do not re-start pc at this point. Continue with the Revo un-install as this program goes a bit further than most un-installers. When you get the window with choices to Select all and then Delete - do so. Continue until Revo has done its stuff, does not take long. When finished you can then re-start your pc to complete the process - you will now have a good clean-slate to re-install your cam software again, which should then work ok.
Good luck - I use the Quickcam Pro9000.