Graphic card change cause Debian to freeze after login
 

Installed debian wheezy 7.1 with another PCI-E graphics card (nvidia quadro fx370) inserted. Now when I change to ASUS 6800GT (EN6800GT) with DVI-cable debian boots and show a rainbow colored swirl as background, everything else is blurred/grainy as well, see pic.

Discovered when using DVI-> VGA adapter and VGA cable connected to monitor everything looks normal, and I don't mind using VGA.

However after entering login password and clicking applications tab system freezes (this happened with DVI as well). Only able to move mouse, nothing responds when clicking or when pressing any keyboard button.

Booted into recovery, gave password for root and tried
/sbin/lspci as instructed in stickied thread. I get "bash: /sbin/lspci: No such file or directory"

Newbie here - reply has to be at an appropriate level.

edit: when logging in as GNOME classic so far it looks good. *knock on wood*

that looks like improperly configured video. Try to remove xorg.conf (if you have). and also try to reconfigure x

Do you have the proprietary drivers installed? That is the only way of using nvidia cards reliably.

The first thing I would do in such a situation is to install the nvidia-kernel-dkms package (if you haven't it installed already, that is.) It is in the "non-free" repos, so you will need to add it in your /etc/apt/sources.list first, so that it reads something like
This would compile and install the proper kernel modules for your new graphics card, would set up your Xorg configuration, and would also keep the driver up-to-date each time you update your system (apt-get update -> apt-get upgrade -> apt-get dist-upgrade).