I have Windows 7 When i start up the computer it goes through the mobo specs and what not than it goes to Windows, shows the Windows logo. Next is supposed to be the user login screen from Windows. About 1 in every 3 boots will it successfully bring me to the user login screen. The other 2 of 3 times my screen just goes black (however my monitor is still getting "some kind" of signal but if it does not get a signal it gives a message that the monitor will now shut off) My keyboard lights are on.. the tower lights are on.. I can hear the fans. Everything seems to be running good except it's having the problems with always getting me to the user login screen. My guess is it's something with windows and not a video card error. I've updated my video card drivers and it's still doing it. Any suggestions?