Strange startup connection to 199.239.137.*

I just noticed this in my Firefox browser. With my TCPVIEWER utility
running, When I start FireFox, within a few seconds, it is making a port 80
connection to 199.239.137.*, usually 199.239.137.200 or 199.239.137.245.

Then within another 5 seconds or so, it closes. So some "pinging" or
spyware crap is going on.

I have exhausted everything short of removing and reinstalling FireFox to
get rid of this unknown connection.

What could I have prepared in FIREFOX that will caused this? This doesn't
happen on a few other machines where I have FF installed nor does it happen
with IE. So it is something I have prepared in my copy of FF.

Could it be some "Tabbed" thing? or FAVICON thing that FF is trying to
update? on my tabbed URL menus?

Anyway, any tips of getting rid of this annoying intrusion would be
appreciated. I hate to reinstall everything without having a clue of what I
am cleaning up.

Thanks

Sam