I also get this once every couple days. Always from the lock screen.
Tested on DELL OptiPlex 755 with : - 01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] RV610 [Radeon HD 2400 PRO/XT] [1002:94c1] : free radeon driver with dual screen, - 01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GK107GL [Quadro K2000] [10de:0ffe] (rev a1) : nvidia proprietary driver 331.79 with dual screen.
It's an important bug to deploy Ubuntu 14.04.
I also get this once every couple days. Always from the lock screen.
Tested on DELL OptiPlex 755 with :
- 01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] RV610 [Radeon HD 2400 PRO/XT] [1002:94c1] : free radeon driver with dual screen,
- 01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GK107GL [Quadro K2000] [10de:0ffe] (rev a1) : nvidia proprietary driver 331.79 with dual screen.
It's an important bug to deploy Ubuntu 14.04.