This problem seems to be related to Windows games explorer. I have this problem since few years ago and at first I use an application to "suspend" rundll32.exe to prevent it from eating CPU. It does work, although it's kinda annoying to do this everytime I start the game.
Here I found a better solution after looking around:
Find a file named "gameux.dll" in /WINDOWS/system32 folder, change the ownership to "everyone".
Now rename the gameux.dll with anything else, for example ga-meux.dll.
That's it!
