Okay, so I thought this might have been a problem with my IIS proxy, because Chrome's console was reporting 502 (bad gateway) errors, but I was connecting directly to the local IP and the same issue came up. The screenshot shows the console while connecting through the local network.
Ubuntu Server 14.04.1 running on a VM (VMware Workstation 9)
NodeBB 0.4.3 master
The rest of the stack is whatever was installed by following the directions here: https://docs.nodebb.org/en/latest/installing/os/ubuntu.html
I have added the imgur plugin (nodebb-plugin-imgur) and the dbsearch plugin (nodebb-plugin-dbsearch) and the local emailer plugin (nodebb-plugin-emailer-local). Everything else is a pretty much stock install of NodeBB. I run this through a proxy usually, but in this case I am circumventing the proxy and directly accessing the Ubuntu server by it's local IP. NodeBB was started with sudo ./nodebb -start (too lazy to worry about the proper permissions for port 80 right now).
I still can't cause it to happen. It seems to recur more often once it's happened once (and closing the browser and opening a new session seems to clear it up for a while) but I haven't found any rhyme or reason to it. And clicking the links listed in the console results in correctly loading items, usually something like:
Please let me know if there's any additional information I can provide.