It is stupidly easy to crash a graphics driver, but if you have TDR enabled then it is difficult to actually kill it if the operating system is not compromised. Simply put, GPU drivers do not offer error recovery features as advanced as, for instance, native code running on a standard processor and operating system. The driver can try and do some logic checking for you before issuing the work to the graphics hardware, by way of return codes - which you should always check, by the way - but once the GPU is busy, the driver has very few options to detect any error conditions which the device cannot resolve on its own - such as infinite loops in shaders - much less tell your application about them.
A lot of that comes from the fact that the current generation of GPU's do not support preemptive tasking, that is, they cannot be gracefully interrupted once a shader or kernel is launched on them. If the driver does not have TDR - which detects when the GPU has stopped responding for X seconds and resets it - then you are stuck with a brick and have to reboot to get the GPU back.
I wouldn't worry about it. Just use the GPU properly and the driver should not crash, if it still does then it is more likely to be a driver bug than faulty hardware. Generally, assuming it is not overheating, hardware is either broken or not. If it worked yesterday, and it passed POST today, then it will work another day.