I am having the same problem. I upgraded frm Mythbuntu 12.04 to 14.04 with the Asus M3N78 motherboard (Nvidia 8200 graphics card & nvidia-304-updates driver).
Using xfce4-settings from Ubuntu 13.10 (as per post #18) fixed it for me. I have not tried using the suggestion from post #10.
I am having the same problem. I upgraded frm Mythbuntu 12.04 to 14.04 with the Asus M3N78 motherboard (Nvidia 8200 graphics card & nvidia-304-updates driver).
Using xfce4-settings from Ubuntu 13.10 (as per post #18) fixed it for me. I have not tried using the suggestion from post #10.
There is another fix in this thread that I'll try later this week -> http:// ubuntuforums. org/showthread. php?t=2221496