I don't mean to scare you but the last time I saw such a crazy display it was because my laptop cooling had failed. Is there any chance at all that something of this nature has happened with you (coinciding with the upgrade)? On a different occasion on a different system there was bug with a viafb (driver?) and everything froze with not even ctrl+alt+del possible. I had to blacklist it for that particular release and use the default VESA driver [https://bugs.launchpad.net/ubuntu/+source/linux/+bug/518623]
I don't mean to scare you but the last time I saw such a crazy display it was because my laptop cooling had failed. Is there any chance at all that something of this nature has happened with you (coinciding with the upgrade)? On a different occasion on a different system there was bug with a viafb (driver?) and everything froze with not even ctrl+alt+del possible. I had to blacklist it for that particular release and use the default VESA driver [https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/518623]