I just upgraded my computer from Ubuntu 8.06 to 8.10 and then to 9.04. As expected, Nvidia drivers needed to be reinstalled and the graphics are all messed up. However, now the screen resolution is locked at 640x480. It appears my screen/monitor is not recognized. I seem to remember having this problem before but I can't remember how (or if) I solved it.

I am using a Nvidia 9500 GT graphics card and I have installed the proprietary Nvidia drivers using System > Administration > Hardware Drivers. Any help would be much appreciated.