Compiz fails, no unity, Blank desktop after 13.04 update

[bogan]

Hi!,
On my second day with Raring Ringtail I booted normally and ran the updates, which I think included some for Compiz, and a reboot was requested.

It rebooted to an normal GUI Desktop with chosen background, top panel and greeter login window. Logging in to Ubuntu gave a Blank screen with no panel or launcher; after a pause a window announced the Network was connected.

'Ctrl+Alt+t' gave a terminal and echo $DESKTOP_SESSION gave: "ubuntu".

In the course of many reboots I had several 'System failures' for Compiz and unity-greeter, amongst others.

setsid unity # did nothing
sudo apt-get install -f # also did nothing
dpkg-reconfigure -a # gave an interactive display

ending with a list of what appeared to be Compiz failures or errors.

Rebooting from 'Recovery>Resume Normal Boot' gave the same result, as did 'Ctrl+Alt+F1 startx', or ' lightdm stop' and 'restart'.

Right Clicking on the Desktop gave access to Additional Drivers but the window had no buttons, or menus, nor size function, so I could not tell which version was which, and as I have not installed any video drivers it is running Nouveau on my GT 520 Nvidia card.

apt-cache policy unity # returns:"Installed: 7.0.0daily13.04.15..." So it is not due to that reported Bug.

In my notes I have a command to reset Compiz, but it is not complete:

dconf reset -f /org/compiz/
# Edited typo 'reset was omitted here, not in original

This I got from:
http://www.webupd8.org/2012/10/how-t...in-ubuntu.html
But it requires a PATH, either a Key or a Dir, Edit: presumably error was because /org/compiz/ does not exist ??

Would someone please tell me what 'PATH' to add? I have a separate /Home partition.

Or what else to try?

After rebooting and logging in to Gnome Classic(no effects) a normal Desktop resulted, so it is not a video driver problem.Edit: But see later Post.

Chao!, bogan.