Might also want to try this:

Also, if anyone is getting black screens randomly with their 4xx/5xx nVidia cards I would suggest to download MSI Afterburner (it's not only for MSI cards), unlock the voltage tweaking option, and kick the stock voltage on your card up a notch or two and see if that fixes the problem. This is usually only necessary for people who are really pushing their cards whether you're playing solo or multiboxing. I was getting black screens and random reboots myself when I was using SLI playing solo but a small nudge in voltage (from 1.013 to 1.025) fixed everything. If you do happen to increase your voltage or change clock settings then make sure to check "apply at start up" or else you'll have to manually activate profiles or move sliders each time you reboot.

EDIT: One more thing to mention is that if you're using an eVGA 5xx card they offer BIOS/firmware upgrades for their video cards
located here.