Hi Chris,
that doesn’t seem the same problem of the Trouble Report you mention, since that only occurs when the screensaver steps in.
We just tested with your same environment and we found no problem, so I would like some more info from you:
1) What is your desktop (Gnome, KDE, …)?
2) What is your desktop manager (gdm, kdm, lightdm, …)?
3) Please send us log files as explained in https://www.nomachine.com/AR07K00677 and send them toforum[at]nomachine[dot]com.