Comment 6 for bug 188389

I have now found a solution to this issue. It seems that I have a hanging glxinfo process which seems to halt the startup of many programs, including metacity.

I have in my initial state 100% CPU usage which is consumed by Xorg and glxinfo. Just by chance I ran 'glxgears' to see if I had good 3D performance. It immediately made glxinfo quit and metacity etc. immediately started and everything was back to normal.

So by running glxgears I crashed/ended glxinfo which made the desktop start continue again.