After re-reading the whole problem, I remember what to do. (I thought X didn't work at all but it seems to work.)
The problem is that the nvidia drivers are a bit buggy on laptops. One problem is the one you have related to terminal switching. (another is related to power management: apm)Somehow you get a blank screen when you want to quit X or when you do "ctrl-alt-f1" (or another combination) to switch to a terminal.
It is a bug in the driver, but there's a good workaround. You need to use a framebuffer console using "vesafb". When you use that the problems will be gone.