When I turn my computer on and the screen appears, all I get is the hourglass (The mouse pointer turns into an hourglass whenever I move it towards the START menu or taskbar) and I'm unable to access my START menu. I usually turn the power off several times before it works again. I just did a virus and spyware scan and they came back clean. Yes, I have Windows XP (Cue the "Get a Mac!" responses). Please advise.