installed on ubuntu, now i can't log in

please help, i installed a driver on ubuntu and now i can’t log in.
i installed the driver that the nvida website recommends on ubuntu 13.04. i can log in on the guest sandbox account and i can run nvidia-settings there. ubuntu installed 304.88, i installed 319.32 (i think). i can install either using the nvidia installer and the new driver shows in nvidia-settings. has anyone here seen this before?

googled, repeatedly reinstalled various driver versions, completely reinstalled system.
time wasted = most of a day

Of course no one has seen this issue as NVIDIA drivers have nothing to do with the login procedure. Login is handled solely by PAM.

If Ubuntu installed 304.88 for you, that probably means you have a GPU older than the 8000 series and that means you need the legacy driver.