I dont know what on earth happened to my iMac yesterday, but its just suddenly gone so slow. It feels like I'm using a windows based PC. I havnt added any new programs/apps or anything. Lots of hang ups, programs load slowly, web browsers are slow to respond, constant spinning wheel of death.........even basic word documents take forever to load up. I havnt done anything to the machine and theres over 100GB of free space out of 500GB on the hard drive. Any suggestions on a cure?