I'm sure about the exact setting, but you want to check the OU that the users account or computers are in. Check the GPO, the desktop setting should be in User Configuration/Administrative Template/Desktop
I'm not too sure about the CD problem. I'll look into that later on.
You should download and install the GP manager console, it's much easier to find the exact setting being applied. Remember, if you install this you can not go back to the default GPO manager!