But I don't have four monitors

I did a recent clean install of Win7 on a Gigabyte-based PC. GTX275 video card. After having windows suddenly black out on me several times after starting, I right clicked on desktop and checked "screen resolution." It shows three monitors (I have just one). So I went into device manager -- it shows two "Generic PnP" monitors, and two "Generic Non-PnP" monitors. Removed the two non-pnp and one pnp and rebooted -- they are back again. And again my system randomly decides, from time to time, that one of these non-existent monitors is my primary, and blacks out on me. (This is the only reason I care -- aboyt 50% of the time, I have to reboot because the video signal fails right before or after I login, I assume because it has switched to a monitor that doesn't exist.) Any ideas?

Or there's a bug in your graphics drivers. I'd reinstall them.