startx is working for you? Can you open a terminal in gnome and run startx and see what the output is? Before I'd get a new blank X session but now all I get is;
<usual X.org messages>
Initializing built-in extension DRI2
Loading extension GLX
Fatal server error:
no screens found
(EE)
Please consult the The X.Org Foundation support
at
http://wiki.x.org
for help.
(EE) Please also check the log file at "/var/log/Xorg.1.log" for additional information.
(EE)
Server terminated with error (1). Closing log file.
xinit: giving up
xinit: unable to connect to X server: Connection refused
xinit: server error
([ 2097.370] (II) NVIDIA(0): NVIDIA GPU GeForce 9600 GT (G94) at PCI:1:0:0 (GPU-0)
[ 2097.370] (--) NVIDIA(0): Memory: 524288 kBytes
[ 2097.370] (--) NVIDIA(0): VideoBIOS: 62.94.0d.00.02
[ 2097.370] (II) NVIDIA(0): Detected PCI Express Link width: 16X
[ 2097.370] (--) NVIDIA(0): Interlaced video modes are supported on this GPU
[ 2097.373] (EE) NVIDIA(GPU-0): EVO Push buffer channel allocation failed
[ 2097.373] (EE) *** Aborting ***
[ 2097.373] (EE) NVIDIA(GPU-0): Failed to allocate EVO core DMA push buffer
[ 2097.373] (EE) *** Aborting ***
[ 2097.373] (EE) NVIDIA(0): Failing initialization of X screen 0)
Also if you open gnome-tweak-tool and go to theme and change the bottom one, 'Current Theme', that works? Here it does nothing, maybe they've modified it so it only changed gnome-shell themes, only changing GTK+ themes does anything. If I use gtk-chtheme then it all works fine.