Error: glXCreateContext failed
This kind of message appeard on my maching after invoking
glxinfo | grep -i direct
Error was (at least I think so) caused by compiling nvidia-drivers against sources with slightly different version then running kernel (I forgot to update symlinc to kernel sources (eselect kernel)).
The interesting part of it is that X sever started at all!
So far I tought that after such compiling X will not start as it happed to me couple of times earlier.
(running kernel was 2.6.32-gentoo-r6 and drivers were compile against -r5)