So this seems to be a huge issue with the latest kernel. I've found reports
I have the same issue after installing an Nvidia GTX 580 and an Intel 510 SSD. Currently I'm stranded in the land of Windows and I'm desperately trying to get my dev box back up and running. (8GB RAM on a builder box so yes, I do need 64 bit)
Has anyone encountered this issue and found a work-around to allow the Nvidia drivers to be used? Is there an alpha or beta of 12.04 which may work?