https://bugs.freedesktop.org/show_bug.cgi?id=39175
--- Comment #3 from Siganderson dj_def@webmail.it 2011-07-12 13:51:56 PDT --- I'm closing this bug, as I discoverd that it was my fault: I noticed a /etc/ld.so.conf.d/GL.conf file that told kubuntu to load files in /usr/lib/mesa before /opt/xorg/lib (as I specified in /etc/ld.so.conf). I discoverd this thing reading the output of glxinfo| grep Mesa that reported 7.10.2 instead of 7.12-devel...
I edited /etc/ld.so.conf.d/GL.conf in this way: /opt/xorg/lib #/usr/lib/mesa
and now things are working correctly.