1st of all, It's not a crash!
It is just slow, when I type fast the characters appear five-five and not one-by-one. When I move the mouse around inside the text editor I get 100% cpu usage.
I did the following:
 * 
reconfigured xorg to get back the default xorg.conf of ubuntu  Used the "nv" driver and retarted X bla bla...  
Results: the same exactly promblem
 * 
Tried to use the "fbdev" driver (You told me something about the framebuffer driver, this you mean?)  Couldn't start x with various of problems that I cannot solve
 * 
restarted X with my usual xorg.conf and DISABLE everyplugin (even compiler)  I opened a c++ file with some code and tried to write...   
Results: the same
 * 
(GNOME:) I went at system->preferences->fonts and disabled hinting and smoothing of fonts (really ugly but font rendering is way faster)  Results: C::B was exactly the same slow when typing scrolling etc!
I don't know what's the prob, I am now preparing to build a custom kernel to see if thing changed. On the other hand I am looking around at ubuntu forums as well to find a solution.
(I am here to do whetever tests you want 

 )