Have the host try switching to windowed or fake fullscreen mode.
You can both try lowering the game resolution and/or graphics settings, and see if that makes a difference.
Running in Windowed mode on the host has corrected the issue. Any idea how to make this work without being in windowed mode, or what may be wrong? The host comp seems plenty capable - Windows 7 Pro SP1 64 bit, 8 GB RAM, i5-4690k, NVidia 970.
Is any of that under spec?
