Msn doesn't work when using dsl router in bridge mode

[hadi57]

hi

i am using 5 pfsense boxes in different location for testing purpose, i am using 2 kind of dsl routers, usrobotics and speed touch, both kind switched from pppoe to bridge mode, i ended up with msn messenger not working on my client's pc who uses windows, the strange thing is that msn messanger is working with ppls using kopete under linux.

i checked the diagnosting, system logs: firewall, i found the followings:
act: x, time: Jul 31:23:36:41, if: wan, Source: (tos 0x0, ttl 1, id 38426, offset 0, falgs [DF], proto: IGMP (2), lengh: 28) 192.168.5.1

and this message apear every time a client try to access msn massenger, with error
any body faced this kind of problem?