The only thing I'm aware of that could cause this is if there is a line in xorg.conf that has the option "VTswitch" set to false (or something similar).
Although I doubt that a default X configuration would come like this, but check your /etc/X11/xorg.conf anyway...
In any case, you can try starting Vector in textmode (or run "init 2") and see if the problem continues.
At least, you'll be able to see if it's anything to do with X.
Also, check in your running processes if you have several "/sbin/mingetty" processes, to see if the terminals are even starting (or look at /etc/inittab to see if they are being launched).
If the problem is not in X and the processes are running, I'm out of ideas... Maybe something to do with your keyboard.