Comment 3 for bug 295991

it's definitely the nvidia drivers, since using the software renderer doesn't exhibit any of the artefacts I see in the NX sessions (in Metacity obviously, since Compiz doesn't run in software rendering anyway)

It's probably some incompatibility the drivers have with the new Xorg in Intrepid. I'm not sure if the Ubuntu devs can do much about it, although one can always hope :)

PS: Gianpa, I have a similar gfx to you (NV28 - mobile GeForce TI4200)