Note - The above only applies to people with Nvidia Optimus

We could get a good idea of what's happening and solve the issue faster with a crash report, if you don't mind getting that information then it's fairly easy;

Go to the start menu search box, type in 'EventViewer' and wait for the search to complete, select 'view event logs'.
Once you have event viewer open, half way down the window will be "Summary of administrative events", if it's too small to read then collapse the other tabs by clicking their headers.
Under Summary of..., expand the 'Error' drop down, and double click the latest report from toribash (tb.exe).
Click the 'details' tab near the bottom, then 'XML view' and copy everything in that box and paste it here.