.When I read your post I didn't see if you checked with Dell for all the drivers as well as the BIOS updates. There's not much magic here. If the BIOS is out of date you see odd things like this. Same for the drivers. But which drivers are suspect after the BIOS is current? The motherboard chipset driver.

And remember the BIOS and motherboard chipset have to be in sync or you get odd things like this.
Bob