I had the same problem; I discovered I was mixing trusty xorg with utopic kernel... upgrading both to utopic solved the problem:
https://wiki.ubuntu.com/Kernel/LTSEnablementStack
I had the same problem; I discovered I was mixing trusty xorg with utopic kernel... upgrading both to utopic solved the problem:
https:/ /wiki.ubuntu. com/Kernel/ LTSEnablementSt ack