Thanks for writing, wombat. Let me start with a bit of explanation.
The web browser makes two connections to the web server inside the Centipede. The first connection is the typical one that draws on the screen. This is the usual port 80 http connection. Connections like this are transient. In other words, the browser makes a connection, exchanges data and then disconnects.
The second connection is persistent, and where most of the “magic” occurs. The browser and the server try to keep this connection active continuously. It is used to update values without having to redraw the entire page, and to send operator actions to the server.
You can tell when this second connection is no longer active, because on many of the pages, the large “Centipede” at the top of the page will change from blue to gray. It is the lost of this second connection that is causing the behavior you are reporting.
Why is this happening? Likely it is caused by some kind of interference on the network. It will not be caused by using a second device at the same time, for example, unless that is overloading the network (which is unlikely). I assume you are using a wired connection, rather than WIFI?