No audio in messenger 6.10207

I'm running Win XP Pro, NAV 2003 and NPFW 2003. I was
unable to view webcam with the original version of
messenger shipped with Xp so had to upgrade to 6.10207. I
now have video, can chat, but no audio at my end. I can
neither hear nor speak through messenger, though all
checks out in the audio setup wizard. I use a Linksys
modem router with a built in firewall, have checked Plug
and Play comp, firmware update, set a static IP and made
appropriate changes to the ports in the router and
disabled NAV firewall. I have contacted my ISP who could
not help. All to no affect...Will try a dialup modem soon
but none installed yet. I have tested this system with a
friends help, his messenger is also 6.1, he uses Win2Kwith
a dialup modem and it works fine, but he can not hear me
and I can't hear him.. Anything else I might try???

Thanks

Bosco...