OK did you configure your firewalls (McAffee) as suggested. The link above tells how. Even if XP firewall is off, it might be an idea to set it to allow LW anyway, you never know.

Can you tell us more about your wireless. What brand & if possible what model number. These often have internal firewalls & require a port to be opened in some cases for LW.

After LW has been open at least 30 mins can you do this test: Bug Report instructions & sample image Does it say True/False? If it's false then there's a firewall somewhere that's partially blocking LW.