in case you didn't do this yet, disable the uac in windows, remove that nasty junk anti virus that came with the system (if you must use anti virus, use avast free version you can at least shut down the resident real time virus scanners), make sure ah is allowed through the firewall, and test your in game settings in offline mode.
also, under options -> preferences -> view options take the check mark out of "always start in mouse look".