Also check other security utilities you have be they anti spyware or ad, etc. Depending on particular one, they can sometimes block an internet program from working, else even remove part of the program so it doesn't work because they consider it as spyware when it isn't (poor programming or attitude by them.)

Oh & run Crap Cleaner so it cleans your registry. Sometimes old fragments of programs linger, not being removed properly & can muck up the running of the newer version. So a cleaning of the registry will remove such unneeded bits.