Mouse goes to sleep

[R Kimber]

When I use the mouse, the pointer moves without any noticeable
latency.  I can stop using it for a short while and then when I use it
again the pointer moves instantly.

However, if I leave the mouse for a longer period it seems to go to
sleep (although the screen is still active) and when I move it the
pointer does not start moving again for a second or two.  I find this
disconcerting.

Is there a setting somewhere that would enable me to change this
behaviour? [6.06.1]

- Richard
-- 
Richard Kimber
http://www.psr.keele.ac.uk/