is the video card firmly in the slot
is the monitor cable firmly connected
are you testing with a known 100% good monitor?
are you trying to goto a resolution or refresh rate which is out of the monitor's range
i'd try booting into safe mode
see if that gives a viewable image (safe mode runs very low resolution, very low color, and very low refresh, so basically any monitor can run it)
I am uising Windows 98 SE. Over the last month my monitor has been zapping every now and then. Today my monitor went blank. I hooked up another monitor and it boots to Windows (with everything showing on the screen). When it gets to Windows the screen is blank. I now tend to beleive it is my video card. Is this correct?