Did that monitor come with a driver disk? If you are talking about an older model lcd the need for a driver was often the case. A crt monitor wouldn't be seen anyways since Windows already has what it needs for the standard display. Besides any possible fault with the monitor the drivers for the video card may gone on bad when reinstalling those.
Running a screen resolution over what the card will support will also cause a number of things to go wrong. What make and model is the monitor itself? That would useful in finding out if it requires it's own driver set.
It is a NEC multisync FE950
I tried a downloaded driver from the net and it had no affect
I lost the original driver disk (Its around here somewhere) (but I cant find it)
These links are a few things to look over if everything is found ok with the current card installed and drivers there being updated. The lack of any listing for it shows the drivers didn't go in correctly. You may have to use the add new hardware wizard to manually choose from the list of devices there and browse to the drivers in order to have Windows install them.