Monitor goes to sleep at startup

At home, my monitor's been blinking off as if it gets no signal as soon as Win7 goes from the swirly-dot logo boot screen and would normally prompt for login. I can login blind without problem, but the screen only wakes up if I turn it off and on again. The screen's a Dell LCD (SP2009W) that's about to hit its 5th birthday, IIRC. The video card is a GeForce GTX 560 Ti. Plugs are seated properly, though I haven't cracked the case to see if the card is loose.

Anyone experienced this?

It's unlikely to be the card.

Test the monitor with another computer to isolate the fault.
Test in safe mode to see if different resolutions make a difference.

I get this problem frequently plugging crappy old monitors into unix servers that have the screen resolution/refresh set out of range for the monitor. If there's been no change in the refresh rate or resolution settings for your video it could be the monitor's starting to pack it in.

Yeah, that would be my initial guess, too, that the monitor is starting to fail. Maq's got you covered there... time to test with other hardware, if you have it available, to try to narrow down the problem. Don't forget to swap cables, too, if your monitor has one that detaches.