Graphics configuration not supported

I've been using FCPX for several months, recently I installed Mountain Lion and 10.0.5.
Not, editing, the response of the programs began to slow down and after closing everything down and restarting I get the above alarm. If closing, shutting down, restarting one or two times, it tries to load but it hangs trying to load the present project, if I force quit then at reopening it launches the alarm.
I already had before some issues of recognition of some HDD.
Bug on 10.0.5?, Mountain Lion issue?
My machine is the same since 10.0.3, iMac quad 2,93, Ati Radeon 5750, 8GB ram.
So far I uninstalled FCPX and I am downloading it again. Anyway to keep it on my HDD?
Thanks

Imac 27 Quad 2.93, 8GB Ram, 1GB Graphics, FW800 external + Raid