My desktop is acting up. When I turn press the power button the desktop sounds like its turning on and working but nothing comes up on the monitor neither do the mouse or keyboard lights turn on... I've tried restarting the computer, connecting the mouse and USB to different USB ports. it seems like the desktop is no sending any signals out. It was working fine yesterday. I left it on overnight and wasnt working in the morning. any idea why that would happen? System beeps when I turn it on... could this be a motherboard failure? Thanks