I've had this issue for a long time now. The computer is still running, but the monitor will lose signal and the keyboard and mouse will stop working. I've tried replacing the monitor and cables, still happens. I tried replacing the ENTIRE COMPUTER... still happens. Clearly it's not a hardware issue. None of the hardware is the same. I'm on a brand new system with nothing left from the previous computer. But it's still happening, so I figure it's got to be a software issue, but I don't know how to find out what it is. I've tried looking at Event Viewer, but there's nothing listed for the time stamps that this happens.