I'm having the same / similar issue with lucid Alt Control F1 usually takes me to a flashing cursor no login, occasionally it works as it should and takes me to tty. Some times to return to graphical Alt Control F2 works rather than F7.
I'm using 32 bit lucid with an Athlon64 a GeForce 7300 LE and the 195.36.15 nvidia driver installed by the hardware drivers utility.
I'm having the same / similar issue with lucid Alt Control F1 usually takes me to a flashing cursor no login, occasionally it works as it should and takes me to tty. Some times to return to graphical Alt Control F2 works rather than F7.
I'm using 32 bit lucid with an Athlon64 a GeForce 7300 LE and the 195.36.15 nvidia driver installed by the hardware drivers utility.