Hi I left My Pc open for 2 hours and when I come back I found that my PC is off, I turned on again and start win 7 (64bit) and I search in the system event and I found error event: The previous system shutdown at 2:51:22 PM on ‎7/‎15/‎2010 was unexpected. and there is no bugcheck or any warning above or below that event !! what is the cause for that ??? I tried also sfc /scannow and no errors found Since I installed windows 7 and I experience blue screen for different reasons but that happen every two or 3 weeks ! should I go Windows XP 64bit ?

Hi Welliam, The basic solution is to verify that you have the most recent BIOS available, motherboard chipset.inf and\or drivers and device drivers all for 64-bit. You should have no bluescreens or unexpected shutdowns. Some Windows updates require a restart and ignoring those restarts could cause a problem. I would not return to XP. Instead, verify your hardware and software are updated and compatible with 64-bit.

Hi Welliam Since you were not in front of the computer when it shut down, and there are no events or dump files recorded, there is no way to really determine exactly what happened. It could have been a brief interruption in power or....? If the computer started OK after this happened, then it was probably a minor incident. Hope this helps. Thank You for using Windows 7 Ronnie Vernon MVP

thanks alot for all replaies the problem did not occurred again so I suspect that my PC temperature reaches high so the motherboard shutdown the system , ... right ?

Hi Welliam, I had a very similar situation the other day but the PC closed down in front of me. After a little investigation I found that the procesor was running at over 100c which caused the shutdown. The next day, I stripped the PC down, cleaned the CPU fan & heatsink and all systems go! Memo to self: clean PC fan & heatsink at least every couple of months!

yes yes I suspected that but I left the PC open for 2 hours only !!