Nvidia graphic's card drivers

[Rich Rudnick]

gerald.jean at videotron.ca wrote:
> Hello there,
> 
> I'm on Gutsy Gibbon.  A couple days ago I was browsing: System >
> Preferences > Appearance > Visual effects menu, it was set to "No
> effects".  Unfortunately, for me, I changed the settings to "Extra";
> when I closed the panel Ubuntu said it needed to install some Nvidia
> graphic's drivers to get the desired effect; I clicked OK and the
> drivers were installed.  The computer then needed to be rebooted, when
> it started Ubuntu told me that those Nvidia drivers were not supported
> by Ubuntu, I clicked "go ahead anyway" (very bad idea!), or something
> similar and all the effects worked fine.
> 
> Problems started when I tried to shut the computer down, as soon as I
> hit the «stop» button the screen goes black and a small, moving, white
> rectangle appears saying "Unsupported frequencies"???  Worst yet, the
> computer never shuts down, I have to hold the switch for several seconds
> for it to shut down?
> 
> Needless to say I changed back the above settings to "No effects", but
> to no avail, the damage is done now.
> 
> What do I need to do in order to get the previous behaviour back, i.e.
> the computer shutting down when asked to?  Do I need to uninstall those
> drivers, if yes how do I find them and how do I go about uninstalling? 
> Anything else?
> 

System->admin->Restricted manager, disable the nvidia driver.