I'm running Windows Messenger 5.1, but for some reason I can't send messages
out from within Media Center. If someone sends to me i will receive their
message, but when I try to reply the reply is never sent. So I also can't
initiate a conversation from within Media Center.

If I minimze Media Center I see a corresponding messenger chat window at the
desktop. If I use this window to send a message, the target receives the
message fine.

Any ideas on how I can resolve this issue. Same behavior on extendeer as
well. Which is a pain since I'd like to be able to chat with my son/daughter
who would be watching TV while I'm at work. They can get my message, but not
reply.