Re: nvidia+amd64+2.6.20+feisty = stone dead computer
I have the exact same problem using a 188.8.131.52 kernel I built myself on Gentoo. I can load the nvidia kernel module (modprobe nvidia) without any problem. However, as soon as I try to start X, the screen goes blank, and I can't do anything (VT-switch, ALT-CTRL-DEL, ALT-CTRL-BACKSPACE, etc...). I saw in the driver README that it might be a problem with some buggy BIOSes, so I left my computer like that for 30 mins, and nothing happened.
As you have said, there is nothing written in /var/log/Xorg.0.log.
Of course, in the included log, I'm using the Open Source nv driver since I can't get X to work with the NVidia driver.