Experiencing a problem with my PC in which the computer fails to boot successfully. The long version is I left my computer on while at work.. worked fine when i left. When I returned home the monitor was not responding (floating no signal screen). I attempted to reboot the computer and recieved a windows failed to boot successfully (choose safe mode, last known configuration, etc.) message. I clicked Start Windows Normally and the monitor again stopped responding, the hard drive light stayed on constantly, but no sound could be heard from it. After 10 or so minutes of waiting I hard rebooted it (holding power button in), and this time the power light comes on but the hard drive light does not. The next time i reboot it the windows failed to start message comes back and again the monitor and hard drive stop responding the second i click start windows in either safe mode or normal mode. Then back to the other way (in which the hard drive light never comes on). I replaced the hard drive but that apparently did not remedy the situation (after powering on with new hard drive the hd light comes on and stays on but nothing ever appears on the monitor and the hard drive makes no noise at all). Im exhausted and clueless at this point, please help.