I'm close to the solution. If I run glxinfo | grep renderer as root, I get direct rendering: Yes OpenGL renderer string: Mesa DRI Mobile Intel�� GM45 Express Chipset GEM 20090114 while, if I run the same command as a simple user, I get direct rendering: Yes OpenGL renderer string: Software Rasterizer So I think that's a permission problem now. Have you any idea? Thanks a lot, Massimiliano