My 3rver creates a UDP socket and 3nds it's messeges to a multicast
UDP group & port which clients R joined to.It functions correctly on
all PC's except my boss(!!!!!), which has several IP on it.I made
some check points and trace it. I realized his PC sends packet but
can not receive packet. I think the port which UDP Socket is binded
to, can not recieve packets.

That was the story (kal'ali! ;)) ), is any one who has experienced
something like this?

Is der any function which could check the UDP ports and recognize
whether they R alive :)) or not?

Can Ds problem be solved by software ?or iz it basically concerned
with network hardware?