How do I lose the mouse pointer?

I installed a second monitor for FS9 this week. Very useful to haveFS9 on one screen and FSNav on the other, even if having the cockpit on one screen and spot view on the other drags my frame rates down too much. One annoying niggle though is that my mouse pointer no longer vanishes as it used to. Sits there getting on my nerves. I seem to recall (?) that there is an option somewhere for having the pointer disappear after a number of seconds; maybe it got unticked somehow when I added the second monitor, but I can't find the option, if there is one.Thanks,Martin S.