Yes, the 5100AGN adapter can support IGMP. I suggest you contact your nearest Intel support center if you continue to experience problems.
Thanks for answering.
Can you tell me your driver version?
I used 13.5, but older drivers should work also.
Mine is 13.5.0 but it is unwulling to join the multicast stream!
Are there any specific configuration setting under Advance Tab of the wireless driver card?