This also affects me on Mythbuntu 14.04 x86 64bit with the open radeon driver and ATI RS880 [Radeon HD 4250] graphics controller.
The workaround for me was to disable xfsettingsd in the GUI Settings under "Session and Startup":
1) In the "Application Autostart" tab I unticked xfsettingsd.
2) In the "Session" tab I selected xfsettingsd and clicked "Quit Program".
This also affects me on Mythbuntu 14.04 x86 64bit with the open radeon driver and ATI RS880 [Radeon HD 4250] graphics controller.
The workaround for me was to disable xfsettingsd in the GUI Settings under "Session and Startup":
1) In the "Application Autostart" tab I unticked xfsettingsd.
2) In the "Session" tab I selected xfsettingsd and clicked "Quit Program".