I recently had to replace the mother board in my HP Pavillion a620n because of a nearby lightning strike. The replacement was done by a certified technician. Now when I shut the PC down I must turn off the powe strip it is connected to, turn the power stip back on and then press the power button on the top right of the PC case. Prior to the replacement all I had to do was press the power buitton. I have checked all power settings etc and they are correct. When I turn the power strip back on the hard drive accesss light flickers, the DVD drive light flashes and the fan start. I then pust the power button and the computer boots.