I've just got Gnome with 11.10 up and running with my netbook and liked it so much I thought I'd get my parents old machine sorted with Ubuntu too. Unity works fine but when I try to switch to Gnome shell, I get problems. On login, the wallpaper appears as normal but then the colour bleeds out from the centre, leaving traces of it around the edge in a purple haze (yes, I do like Jimi Hendrix but I'm not making this up).

When I go to applications, typing then pressing enter in the search field dumps me out so there's nothing but File / Edit / View etc in top left; starting a program seems to work but then there's only a white screen and no program window.

Gnome classic works fine, from the limited use I've given it. I'm using an Asus desktop with ABIT motherboard, 2.6ghz with 1gb RAM; I've checked drivers and it says I'm up to date, Nvidia graphics. Anyone any ideas?