Comment 5 for bug 564617

When the screen stays blank, ubuntu is not completely frozen : if I push the power button (without holding it), the hard disk flashes a few seconds and then it powers down : looks like a proper shutdown

I found a temporary workaround by adding startup parameters in grub :
if I add "nouveau.modeset=0 nouveau.noaccel=1 blacklist=vga16fb", the desktop appears properly and ubuntu seems to work fine.