move your video card into another slot. i had a very similiar problem. i used my computer for about a month, then opened it to install something, and once i went to power it back on, my monitor wasn't leaving standby mode. i totally was at a loss...so i switched my vga card into another slot...and it works.
i still don't have a clue why it all of a sudden didn't work. well trying doing...maybe it will work for you as well
Desktop - DualBoot: Fedora 15/Windows 7 64bit
Netbook - Windows 7 Professional
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