This happened twice so far, in approximately 8-10 hours of play. The first incident happened as follows:
I was squatting under an apple tree, successfully picking apples. I pushed the "F" key to search again, but nothing happened. I spun the scroll wheel of my mouse, but I could not get a prompt to search for apples. I got up and walked to a nearby house, but I could not vault over the fence. I walked around the fence, but when I got to the door, I could not get a prompt to open it. Based on the symptoms, I expected to see a "No Message Received" message, but I never got one. I had to log out of the server and then log back in to resolve the problem.
The second incident was as follows:
I had one rifle on my shoulder and one in my hands. I climbed a water tower and when I did, I dropped the rifle that was in my hands. When I descended the tower, I opened my inventory screen, but I was unable to drag the rifle into my hands. I closed the inventory screen and I tried to get a prompt to pick up the rifle, by hovering the curser over top of the rifle. This strategy did not work either. As before, I tried to interact with other objects (I couldn't get a prompt to climb back up the water tower), but I could not. Under the circumstances, I expected to see a "No Message Received" message, but I never got one. I re-logged into the server and the problem was resolved.