Running xp pro and Windows Messenger v. 4.7.2009.   I cannot send files, voice or video.   Error says that transfer is blocked and to contact my isp which is Comcast Cable Internet service.  They say they have nothing that will interfer with WM transfers.  I have a Lynksys router  that has a fire wall and Lynksys support artical says it cannot be turned off .  The aritical suggested I try turing off my other software firewall which for me means only the firewall  that comes with xp pro, which has been updated by SP2.  With the xp firewall turned off I still cannot send files etc. with WM.  I have tried this with two friends who have  broadband but I don't know there firewall situation.  Any help??  Is there an artical somewhere that will give me a check list or more info??
Doug

http://www.microsoft.com/technet/prodtechnol/winx...eploy/worki01.mspx
Maybe that will help you?