Hi I am feeling a problem with windows vista. Whenever I change power plan from "Power Saver" to "Balanced" or "High Performance" it shuts down within few minutes (Maximum half an hour). I thought my vista operating system has become corrupted so I formatted my PC and installed a new fresh copy. I have all latest updates of drivers and vista. But it still creates same problem. I am feeling this problem from last 8 months. During these 8 months I have formatted my PC 3 times and installed new fresh copy to solve this problems but it didn't work. It never shuts down in "Power Saver" power plan whether I don't shut it down for 4 or 5 days. But in "Balanced" and "High Performance" power plan it always shuts down. It doesn't show any error message and most of the time it starts without showing a message of unexpected shut down. It shuts down in the same way as vista shuts down due to data prevention. Sometimes it shuts down even if I am not doing anything and no application or file is open. Please let me know what is the problem? Is it something related to hardware or its a heating problem? How can I solve this problem? Thanks.