Goes LOS and don't come back. the Usual fixes :
Fully remove the Video driver using a good guide (and following it closely). http://forums.nvidia.com/index.php?showtopic=169555 , also unistall the monitors in device manager. Reinstall a driver aquired from the nvida site. Notice thier notes about temporarily stopping windows update from plopping in a driver. There isn't enough room here to tell you how poorly the autoinstalled Driver from MSupdates worked for me.
Reseat the video card. Even if it works most of the time, a poor connection could be the cause, of it not resetting or waking back up.
Lock speeds on GPU to 1 speed, and Raise the fan speed to rediculous noise levels, for TESTING. IMO the temps they allow these cards to get to is beyond logic even if it is "within spec". The video cards Rams are often in the worst situation, and without a thermal monitor to even know how they are doing. Many overclocking utilities give you the ability to do that, without overclocking.
Watch your overclock. I wont say dont overclock :-) but you should know if your overclock is effecting it, it certannly can Both the Bus link and gpu and even memory issues. Also check your PCI-E link width in CPUZ mainboard tab, When overclocking.
Test hardware. When overclocking we always test the heck out of the hardware to insure 100% stability. You dont have to "overclock" to use those same tools to achieve 150% stability ,at standard speeds.
First you need some temperature monitors, for both the System chipset, the CPU and the GPU. Manufactures own temp tools, Speedfan, Everest, Gadgets, CoreTemps, whatever works with your specific hardware, getting the right temp monitors are very hardware specific.
The Intel Burn test, wicked test , but a computer that passes it is stable for CPU and some for memory. I pick it because it does some mean tricks that tests VRM different from the usual prime.
Furmark, only tests the GPU for the GPU doesn't really test GPU memory well. also tests cooling of the GPU. A good GPU memory test is even more important (GPUtool is one). Say the GPU wasnt doing anything? ok, but if it isn't stable and cool, it can crash when "idle" even.
Memtest86 , making a USB or CD for testing the mainboard memory, any single failure means a lot more than people can think.
OCCT , can test many aspects, and test them together which can help test for a Power Supply issue some.
Some people think these tests are too harsh, and a computer doesn't have to pass them. Or that normally a computer would not have to work that hard, so why bother. They are correct. but they are often less stable. When I get a computer passing all this junk 100% for hours on end, the hardware itself is no longer suspect.
If Any of this stuff fails, It does NOT mean the hardware is bad, it just needs to be tweaked a bit. Or cleaned , or the use of a utility to improve on default settings.
Sum Things that can change the display, thereby causing a black screen between.
Log-In display that is a different resolution. it is possible to have a log-in screen that is at a different resolution than the desktop screen. (still looking for referances)
Live Mesh - HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Live Mesh\Remote Desktop\DisplayDevices\DEVICE0 Setting for remote screen is different , if you use live mesh.
Color Calibration loader :
From Shobogenzo Microsoft answers user
Start->Administrative Tools->Task Scheduler->Task Schedule
"WindowsColorSystem" and look up and you will find "calibration
loader" top panel. Highlight it and go over to the right and
under"Selected Item" you will see "Disable". Disable it. now you will
see that the calibration loader is disabled.
The Refresh rate: I notice my monitors refresh rate is set for 59 by driver, I reset the refresh to 60 , probably some aspect of the system is still set for 59, causing it to to change that.
-User Based items, could change between users?
Compatability mode any program that was put into low res compatability mode , that is starting up, even if it doesnt open a screen itself.
Change in "effects" because both the log-in and the main display use the new "effects" like shadows and animations. Mabey a difference between the settings on both incurs an unnessisary refresh. Changing text shadow referance
Change in DPI between the log-in and display: or between users. Seven Forum Unsolved
Aero or classic theme change: