First time I've ever seen this. I sent one of my ships to attack a Thalan ship. I got the confirm battle window, and clicked to see the battle. But the combat viewer didn't appear - I was left looking at the main map while listening to sounds of combat from the battle I should have been watching. I could move the cursor and click on things, but without result except for an occasional sound effect (like the sounds that say "you can't do that"). The keyboard was unresponsive, I could not advance anything using the tab key and the escape key didn't bring up the main menu.
I finally had to bring up task manager and kill the game.
The debug.err file is filled with these messages:
Debug Message: ERROR: (CD3D11Renderer) Failed to create a vertex buffer ((887a0005) The GPU device instance has been suspended. Use GetDeviceRemovedReason to determine the appropriate action.
I've opened ticket #NSZ-259-61315 for this problem.