I've had my imac for 2 yrs now and haven't had any problems up until now. Now it's running slower to start up and my mouse is moving on it's own. I don't use a mouse pad and I haven't had this problem until recently. Could someone be hacking in my computer? Could I have a virus? I have been watching movies online but I don't download anything BUT the problem has happened after I watch movies. Could I have done something to cause this?