This happens, seemingly at random, both when visiting forums such as this one, and now, when in the blender console. Most commonly it'll be as if I'm pressing and holding either the enter key or the back-space key. ctrl-c seems to stop it. Pressing other keys might also stop it, I'm usually rather frazzled when it happens. So, I guess, the first question is, has anybody else reported anything similar? Hard to search for if you're not sure how to describe it..