Hi all, I have a custom built computer, fairly new. Everything has been working fantastic until yesterday. The computer was in a "standby" mode, so when I moved the mouse it tried to bring the picture back up on the monitor. I noticed, in the very brief time it remained on the screen, that the font size was very large, as if the resolution had been reset back to 800 x 600, which it had not. Immediately the screen went blank and I got the message "No video signal". At first I thought the monitor had gone kaput so I dug one out and hooked it up without success. Next I installed a new video card, also without success. All of the cables are hooked up correctly and the card is seated correctly. LISTENING to the "beeps" in sounds as if Windows Vista is loading normally, just can't tell for sure without a picture. Also replaced the video cable. Any other suggestions would be very much appreciated at this point. THANKS in advance for any ideas of help you can provide me with.
Do you get any image on the screen at all? Like the BIOS screen?

This is a long shot, but you could TRY clearing CMOS.can you see it during POST?No, there is no image at all. Absolutely nothing throughout the boot up process.Well, good news, as the problem is solved! I did not realize that I had integrated video on the mobo, so I hooked my monitor up to that. Lo and behold it booted up just fine, although in VGA mode, but it looked just GREAT to me, at that point.
So, just out of interest, I tried hooking it back up to the new video card and it also booted right up?! I'm still pretty CONFUSED by all this, as I had tried this same thing repeatedly the day before, without the integrated video step, however.
However, as long as it is working now, I'm happy.
Thanks to those that replied.