vnc quality problem

I have a couple of servers with openSuSE 11.2 which I access using VNC through the local network.

All is fine from the windows computers (Vista & XP) using tightvnc and the laptop with openSuSE 10.3. I have desktop image quality problems from the openSuSE 11.2 desktop - tightvnc 1.3.9.

With full colour depth (16 bit) I get rectangles of the screen which look like noise. With BGR233 I get a useable desktop but the image quality is low.

It is a bit embarrassing that the only desktop with a problem is the 11.2 one!

Any advice on how to fix?