xbox 360 connection problem mce vista

I have a connection problem between the xbox 360 and vista media center :

- The 360 mce connects fine to vista 1 time per reboot
- After i close the mce on the 360, the 360 cannot find the media center pc
anymore unless i reboot the pc.

The 1 time per reboot that i do get a connection, everything works
pictures/music/video all o.k.

I tried to fix this by trying the following :

- Reboot router
- Reboot xbox 360
- Switch off vista firewall
- remove nod antivirus

In the event log i can always see the first connect from the 360, but no
close and no further connects until i reboot the pc.

I can see the xbox always in the network and sharing center so the
connection seems to be fine.

If anyone has an idea it would be great since the mce function of the 360
looks and works great.

Some extra info :

I installed vista again just to be sure (fresh with the updates) :

Same problem, media center finds the xbox360 without any problems and the
first time i log in on the 360 everything is 100%.

After i exit the mce on the 360, i cannot log in anymore.

I still suspect the router, but a reboot of that does not help and why would
i be able to connect the 1st time....

Really at my wits end.

I have the same exact problem!!!!! I have searched on the internet with no
help. If I find something I will be sure to post the info here. I am using a
linksys router (wrt54g) and linksys game adapter wireless bridge (wga54g).
Both worked fine with Media player 11 for music and pictures. Now with media
center I am having this problem.