This just started happening yesterday and no happens pretty often. Sometimes when I reboot it will start right away, sometimes it will take a few hours. Suddenly an application will stop working or responding, so I will click the mouse onto another window, it will become live most times only to hang. Same thing I try to open the menu, it will pop up and freeze up. The only way out seems to be a hard shut down by holding down the power button. I have a brand new (well, 2 months old) iMac with all the latest software updates installed. Can anyone please help me Thanks guys.