I recently built a couple of render nodes for my home office. During the process I ran into an issue where Max was falling over immediately after opening. After stuffing around re-installing a few times I tried changing the graphics mode to Legacy Direct3D and presto, all is right with the universe again.
In summary, if you're running integrated graphics, for example, in a GPU-less render node situation, you'll want to set Max to Direct3D as it seems Intel integrated graphics do not support the Nitrous viewport.