I just installed Ubuntu 11.10.
I changed the open drivers for the proprietary ones and had all sorts of problems while trying to make dual screens work, so I decided to roll back the drivers.
Now Unity won't start and if I run
/usr/lib/nux/unity_support_test -p I get:
/usr/lib/nux/unity_support_test: error while loading shared libraries: libGL.so.1: cannot open shared object file: No such file or directory.
I tried mostly everything that was suggested on the net with the purge and everything.
ccsm and adding the Unity plugin did not work. I also just learned about that missing file while writing this question, so thats where I'm heading now.
If you need more info just say so.