Streaming to an Airport Express problem

Hi all,

I have a very strange problem that I hope somebody could throw some light on as to what is happening.

I have a Airport Express connected with Ethernet to a router. Further down the network connected to another router in bridge mode I have a Windows 7 computer and an iMac. I am trying to stream music from either iTunes or Winamp via Airfoil on the Windows 7 PC to the Airport Express, but they are unable to see it on the network. That is until however I power on my iMac, and after about 20 minutes or so the Airport Utility and iTunes on my iMac suddenly see the Airport Express (they do not see it straight away upon boot). The moment this happens all the software on my Windows 7 computer can see the Airport Express.

Any ideas as to why I can not see it on the network on my PC? Airfoil is designed to see them, even the iTunes software can not see it. I know it would be better to stream from the iMac but I am needing to move away from it for the moment and use a Windows machine.

Any help would be appreciated.
Thanks,
Andrew

Can you describe how everything is connected?

I get that your router is connected to the Airport Express by ethernet cable.
I take it the router has a built in modem or has a modem connected to get internet?

Does the router provide a wireless network?
Does the airport express provide a wireless network?
How is the iMac connected to the network?
How is the Windows 7 machine connected to the network?

Are the iMac and W7 machine connected by cable to the bridge router and that in turn connects wirelessly to the router or Airport express?

Is the main router the only DHCP server?