window-point oddity

[Harald Hanche-Olsen]

Something odd has happened to my current running emacs:

Whenever I split a window with C-x 2, I cannot move point in the new
window. Or more precisely, whenever I select the new window then the
cursor jumps to the same position it has in the original window. If I
move it away, by any method whatever (arrow key, mouseclick, elisp
executed from the minibuffer), it jumps back to its original position.
There is always a delay before the point jumps. The delay is of
variable length, but never more than a second.

Unfortunately, I am unable to reproduce this if I start up a different
emacs instance. Hence my question: Could I accidentally have activated
some feature that has this (rather annoying) side effect, or is it
more likely that I have come across an obscure bug? (It goes without
saying that if I figure out how to reproduce it, I will report a bug.)

- Harald