I upgraded from 10.10, 64-bit to 11.04 this morning on my Acer Aspire Laptop via Internet. The install completed without errors and when it rebooted I logged in as usual. Then I found there was no window manager running. There was no panels, no window decorations and even the Alt-F2 keystroke failed to bring up the Run dialog.
I had to create a Desktop Launcher to bring up a terminal. I could open an ODT document on my desktop (was surprised by Libre! I assumed that Open Office would be reinstalled) but could not move the window. When I left-clicked in the lower right resizer, it brought up the right-click context menu. I could start up Chrome from the terminal an d that wonderful application does allow it to be moved around without the window decorations.
I logged out by killing the session process. When I logged back in, the same problem persisted. Then I logged out and logged in with the Gnome (safe) session. That worked and brought up the desktop I was used to (i.e. no Unity). When I tried to log in again via a normal session, the problem persisted. With a Gnome-classic session, I have all the functionality I had prior to the upgrade.
Sounds like a compiz problem. Assigning package.
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