This problem has been perplexing me for several months now, ever since I upgraded my server to 12.10 Quantal. Finally found a solution (Can’t remember the site where I found it though)! These are the instructions for a profile that’s already been configured that no longer works.
- Open the NX Client for Windows (in my case).
- In the Session section, select the session profile you originally created, that no longer works.
- Click Configure.
- Under the General tab, and the Desktop section, ensure that Unix and GNOME is selected.
- Now, in the same tab, in the Display section, check the box next to Use custom settings, and click Settings.
- Under the Performance section, check the box next to Disable the render extension.
- Click Ok, then on the next screen, click Save and Ok.
- Now try to connect!
Worked for me at least.