I've had this issues across multiple machines and multiple versions of Ubuntu desktop (all 10.04 or later). Usually it happens with an old laptop I've put Ubuntu on but now it's happening on my primary dev machine (a quad-core PC recently upgraded to Ubuntu 12.04 desktop). The problem is this - I can connect to the machine and login with the password, the initial screen looks fine but never refreshes. I can see the monitor for the machine across the room and can see the mouse move and the menus pop up but the image of the screen on the PC in front me running the VNC viewer never updates. So the mouse and keyboard commands are working.

• Ubuntu 12.04 Desktop
• Ultra VNC Viewer (also seen with RealVNC's free VNC viewer)
• Desktop Sharing Static IP on eth0; Dynamic ID on eth1

I think it is an Ubuntu config issue because this PC used to work just fine with 9.04, 10.04, and 11.10 (over the past couple of years). I've also had a couple of laptops that used to have this issue with older Ubuntu's but don't with 12.04.

Additional info:

The Win7 PC I'm trying to use to control the Ubuntu PC is connected via 2 DLink 8-port gigabit routers. The Ubuntu laptop I usually control via VNC is typically only connected to the network via wireless. The screen refresh is choppy but usable. I've repeated the issue on a Win7 laptop which was connected via ethernet and wireless.