Today I installed some update package and an hour or two later when I restarted my machine, Unity was running in 2D. There were two Radeon packs in those updates which I suspect are the culprit. I attempted to purge the fglrx completely and do a fresh install of the AMD drivers (currently running with AMD HD 7400m gpu and Ubuntu 12.04 LTS) but I did not manage to purge it. Does anyone have any suggestions? Million thank yous in advance!