I did an upgrade from 11.04 to 11.10. Unity 3d becomes a black screen after pressing the dash-button or after pressing alt-tab to switch between open windows. I can see the panel on the top(lock,sound,..) and the panel on the left (launcher) but the rest is black.
It looks like a maximised black window. The open Windows are active but I cant see them. I logout by pressing logout in the right top corner and pressing enter (because logout is default focused on the dialogue screen) and leave unity3d.
Unity3d worked with 11.04 very good. If I press the dash button the dash looks like an 16-Bit or 8-Bit window and buttons for maximise, minimise and close are displayed and looks inverted.
I have rebooted my notebook just now and log in to Unity 3D and tested some features of Unity and everything works well. The black thing is only a layer. I can use my desktop but cant see anything because of the layer, but everything works. It seems so, that a layer appear when pressing dash or alt-tab and does not disappear when close dash or choose a running app with alt-tab. you will see the necessary info related video problems:
/usr/lib/nux/unity_support_test -p OpenGL vendor string: X.Org R300 Project OpenGL renderer string: Gallium 0.4 on ATI RC410 OpenGL version string: 2.1 Mesa 7.11-devel Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: yes
lspci -nn | grep VGA
01:05.0 VGA compatible controller : ATI Technologies Inc RC410 [Radeon Xpress 200M] [1002:5a62]