This sound like your Registry Filters are corrupt. A simple Script tool will cure this. No harm in running it but I will have to source it first. Their is manual Registry edit but can be tricky to do if your not familiar with your registry.
If you need to do it manually, follow the steps in the Vista section to remove the UpperFilters and LowerFilters. I don't use Win 7, so I can't be sure that those registry keys are there but I imagine they are. Be careful when in the registry, don't remove anything else.