Black screen crashes are normally indicative of a graphics driver crash. Under normal circumstances, windows can (if given some time) recover and restart a driver if it crashes. However some graphics cards will lock up with a driver crash and be unrecoverable due to additional issues.
My suggestions are;
Ensure your graphics drivers are fully up to date.
Make sure your graphics card temps are not getting excessively high
Ensure you have enough wattage from your power supply for your graphics card
Double check your internal power cabling to the graphics card for a loose connector
If all else fails;
Remove your current graphics drivers and restart the computer
Get a fresh download of the current driver package for your card
Install the drivers using a "clean boot" procedure (google for guide) to make sure they are installed without interference.
