got an NVidia GeForce 8600 GTS with two DVI-D ports, one hooked up to a 22 inch display, the other one (Secondary) hooked up to a beamer.
Works great for DVD playing etc.
Now, suddenly, today, the screen "Display setting" does not allow me to change resolution beyond 600 x 800 res for my secondary DVI-D output. This of course does not work very well with my beamer.
The slider on the screen does not allow me to change the resolution beyond that resolution.
Also, from memory, before, I had the caption "Generic PNP monitor on NVIDIA GeForce 8600 GTS on both menu items on the drop down menu, now it says that only for the top one.
The entry for the lower one, the secondary one, now says "(Default Monitor) on NVIDIA GeForce 8600 GTS". Could there be a relationship there?
Have you tried disconnecting and reconnecting the second display? You also might want to swap the cables for both displays, and even swap which ports you connect both displays to. Also, can you recall when exactly this problems started? What were you doing or what happened?
Yes, this is probably a driver problem. Happened to me on my OLD OLD OLD OLD OLD (11 year old) ATI... downloaded the wrong drivers, resolution wouldn't go past 6480x800... had to system restore.
Just go to www.nvidia.com and download the latest drivers.
What worked for me was the following:
One of the tabs on the driver context had a link to the NVIDIA control console on the system.
That console then identified both the exact brand and type of my regular monitor, as well as brand and type of my beamer.
Then I had various drop-down options about which one of these was to be the main monitor.
Chose the display as main and the beamer as secondary, and, presto! everything was fine again.
Was able to choose the best resolution for monitor and beamer separately.
Turned out, btw, that the highest resolution on the LCD did not render the best results in terms of fuzziness. Seems that the so-called "native" resolution gives best results.