I have a Compaq Presario CQ71 notebook, nearly a year old, running Windows 7. Lately, the notebook sometimes does not boot. The Compaq splash screen shows, allowing me to press ESC to access various tests of memory and hard drive and to choose which device to boot from. If not pressing ESC, the hard drive light sometimes diasappers and the screen goes black. If I turn off and on the notebook again a couple of times, it usually boots. Sometimes the notebook boots at the first try. Any idea what could be causing the trouble? I have run some tests of the memory and hard drive, and there seems to be no problems with that.