I'm glad it worked for you too. I watch a lot of movies with my laptop and the stuttering was really annoying! Let's hope Dell fixes the driver soon. To be honest I don't know what the device is for but I suppose it has some use! ;)
I found a solution that works for me:
Control Panel -> Device Manager -> System Devices -> Right Click on [Dell Diag Control Device] -> Disable
In my case the drivers for that device updated automatically and since then I started experiencing the problem. I'm not sure if Dell is going to fix...
I have the exact same problem. My system is a Dell 7720 (Dell Inspiron 17r SE). I had the impression the issue manifested after updating the geforce drivers but a clean install (the nvidia installer has the "clean install" option) of the ones available on the manufacturer (dell) site didn't...