Windows will use generic drivers, which with GPU isn't the best. With the GPU, it's a fallback driver for when you haven't installed any drivers (yet) so you can still see the screen and download the GPU driver.
The chance of Windows downloading broken or malicious drivers is nihil, there's an extensive list of tests that drivers from Windows Update and other WHQL (Windows Hardware Quality Labs) signed drivers must go through that's known as the Windows Hardware Lab Kit which is a test framework. This test framework tests drivers on different platforms and configurations to see if the driver is compatible with different versions of Windows.
When I install the GPU driver, I always make sure I'm not doing anything with display or audio to avoid problems with things like what you mentioned.
