Comment 10 for bug 1507676

I would think this mis-reported issue will also be going on with 14.04.4 lts which will not include the so-called ubuntu-drivers-common 'fix'
If interested on what really is occurring on optimus laptop & nvidia-prime see here -
https://bugs.launchpad.net/ubuntu/+source/ubuntu-drivers-common/+bug/1501041

14.04.4 lts users can solve with a start up script(s) that put the display to asleep & then wake up or they can adjust the greeter time to sleep to 2 - 4 sec's. Once sleep > awakened on the greeter then the logged in session will be fine.