Hi Sandy,
After extensive testing we found out that the issue is indeed within the Intel..
As seperate ports multicasting works just fine until now with a lot of tweaking, in a bonding it works as well.
But the moment you place them in a bridge they stop working with multicast.
We tried 2 different cards as well now, 1 from Broadcom and one from Emulex and without doing anything multicast starts working just fine.
So this is definately a problem with your cards, and I have been told to give you an ultimatum of 2 weeks to get this mess fixed as otherwise we'll be looking into using other cards. As aside from a whole lot of time this has cost us a whole lot of money because of being behind on this project now.
Awaiting your reply.