There seems to be more going on than just nvidia driver trouble. I have just installed 12.04 64 bit on a third machine with a more modern nvidia card (Geforce 9) and neither nouveau or nvidia driver will run unity. Thats three fails. Just a blank desktop (wallpaper) which seems to be a very common fault (tried most of the fixes). 3D drivers are working fine, excellently in fact. So it seems to be a compiz or unity bug.
There seems to be more going on than just nvidia driver trouble. I have just installed 12.04 64 bit on a third machine with a more modern nvidia card (Geforce 9) and neither nouveau or nvidia driver will run unity. Thats three fails. Just a blank desktop (wallpaper) which seems to be a very common fault (tried most of the fixes). 3D drivers are working fine, excellently in fact. So it seems to be a compiz or unity bug.