I have a Precision M4700 with 2 monitors connected, went to update the video driver and immediately got crazy flicker and blinking. This machine has 2 different video drivers, i had to disable the Intel 4000 driver, but then, of course, could only use one monitor. so reverted back to a earlier version of the driver...
www.dell.com/.../DriversDetails;fileId=3465609412&osCode=W764&productCode=precision-m4700&categoryId=VI
after installing the older version it worked fine.
Hope this helps save somebody a couple of hours of heart ache and head ache.