I just had a weird problem, that I never encountered before. First, Itunes would not load up, got the spinning icon and I forced quit. I then continued using the computer on-line and then put into sleep mode like I always do. When I tried bringing it out sleep mode I got nothing, not even the power button would work. It was like the Imac was dead. I unplugged it, waiting a few seconds, reattached the power cable and ever thing is back to normal. Should I be concerned about this? TIA.