Folks, I have been facing couple of issues with my laptop for a week or so. 1. I have noticed that it just hangs after staying in sleep mode for some time. The screen goes blank and laptop does not respond to anything. I need to forcibly shut it down with shut down button. This is not happening every time but randomly (not so often). 2. The other thing which is happening is abnormal shut down of OS X. Suddenly a message appears "you need to shutdown your computer etc etc." I am surprised that this is happening to a Mac. Any Mac expert with some help?? Is it a hardware issue or OS? Thanks.