KDE won't start

[Eric]

I have posted here before I think about KDE 4.1 not starting, saying 
that KSMserver won't start. I tried starting KDE from the command line 
and I got an error message with a little more information. It says 
"Nvidia OpenGL driver requires CPUs with SSE"

Gnome boots on this computer and so does the other desk manager that's 
installed by default (Xfce?). So why won't Kubuntu boot? My guess is 
that it's some setting in KDE but I don't know what it might be.

Any ideas?

Thanks for your help.

Eric