My laptop used to work fine with Windows 7 Home edition. Today I installed SP1 and now its shutting down abruptly. There are no error messages, nothing in event viewer. It doesn't even say that it was shutdown abruptly when i reboot. Anyone had similar issues with SP1 ? Update: After lot of troubleshooting finally I am able to solve this issue. This is due to (I think its a bug/incorrect implementation) processor throttle functionality in WIN7. It is supposed to throttle down the CPU when the temperature is high and fan will not be able to cool it down (They should use temp increase rate as deterministic policy and not active/passive setting in power policy) , But its not doing that and that's causing abrupt shutdown. I changed my power policy and limited maximum processor speed to 80% (that is correct, I am asking WIN7 to run my CPU slower than what it is capable of) of the maximum frequency. I did stress test at this frequency and everything seems to be ok.