If you've ever played games on a computer you've seen it once or twice: the screen refresh rate drops beneath the playability threshold and you can't do a damn thing. It's because the system is temporarily overloaded and can't process information quickly enough to redraw the screen very quickly.
Anyway, I was in Stormwind and I figured it was just because it was Saturday night; but when I ran out into Elwynn forest where there weren't as many people it was just as bad, if not worse; so I decided I might as well do a hard reboot and see what that got me.
What it got me was a blank screen.
It had not switched to the TV output, I saw after firing up the DVD recorder and blab slab; I unplugged everything but the monitor and switched to the other DVI output on the card and rebooted, and still got nothing. I was getting frustrated and pissed off now; I reseated the video card and there was no change.
Dreading the worst, I went downstairs and grabbed this system's original video card, and put it back in; but there was no change whatsoever: I wasn't even getting the BIOS screen and the monitor was in power-save.
At this point my frustrated rage evaporated and I got curious: WTF was going on? Obviously the video card hadn't died, but something was wrong; and how could I figure it out when the system wasn't issuing any beep codes or anything?
Then my eye fell on the wireless card, the one I installed in June. I thought, I wonder? and pulled it, then applied power and hit the power switch.
Monitor came on, BIOS screen displayed, nice as you please.
Shut the system down, put the nifty video card back in, found a blanking plate for the empty slot, and buttoned her up. The system booted right up and worked fine.
I got that network card in June, damn it.
Anyway, I'm glad the fix was simple.