The monitor has a low power state activated and deactivated by the video card. Either the card is not sending the signal or the monitor is not responding. Swap one or the other for a test.
Amateur here and any help would be appreciated.
I have a Gateway computer (about a year and a half old) running XP with a LCD flat screen monitor.
All was well until today when, after the computer had been on "stand by" mode, the monitor failed to automatically come on when I started the computer up again.
I turned off the power button to the monitor, then turned it back on again and received the message, "no signal".
After checking to see if the connections were all secure, I restarted the computer (not just "stand by") and the monitor came on as normal.
I tried "stand by" again with the same "no signal" results.
I'm at a loss. Don't know if this means I need a new graphics card or perhaps to at least check if it is seated correctly.
Any help would be appreciated.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic