I've installed NX Server on Ubuntu Maverick Meerkat (10.10) using the instructions found here: https://help.ubuntu.com/community/FreeNX
I have a problem using the default NX Client for OS X (10.6) downloaded from the nomachine website.
When using the OS X client, every time I hit the lowercase d key in the NX session window whatever remote window I'm using minimizes. This only happens in OS X, from the Windows client I have no such problem. This happens from two different OS X machines, so it's unlikely to be a local setting.