Firstly go to the Nvidia contol panel and go to manage 3D settings , change the power management to Prefer maximum performance , leaving it on adaptive is known to cause this problem. Open Firefox and see if it crashes.
If it still happens then remove all your Nvidia drivers , download the latest ones from Nvidia and do a clean install.
If it persists it sounds like the gpu render for firefox is making you crash. I don't use firefox , but check in the Firefox/internet options if you can disable it to software render instead, I know this option is available in IE9.