Secondary Dell Monitor stopped working right!!

Hi everyone, I've been pretty frustrated with this problem and don't know what it to do—I've tried everything I can think of!

I got a Dell XPS 17 in March this year. A few weeks ago, I got a Dell U2412M to use as a second monitor in my studio at school. I've been using an HDMI-to-DVI cable as my laptop has an HDMI port but the monitor does not. It's been working fine. I usually just plug in my computer when I get to class and unplug it when I go home.

Everything was working fine and my computer recognized my Dell monitor but it just stopped working right yesterday. Now when I plug it in, the highest screen resolution I get it 1280x720 (it should be 1920x1200). I also noticed that my computer doesn't recognized the monitor as a Dell. It's calling an a "Generic non-PNP monitor."

I tried these steps to fix it but nothing's working:

• System Restore to earlier working date.
• Uninstalling nVidia drivers and re-installing them.
• Reinstalling the Dell U2412M driver - Nothing happens when I tried reinstalling the monitor driver.

I was on the phone with Dell for over four hours yesterday trying to fix it and got nowhere. I didn't install or changed anything my computer... it just stopped working out of nowhere yesterday. Does anyone know what could be wrong?