Airport Express with Airtunes Drop-Out

I have an airport extreme base station and have recently purchased an airport express with airtunes. I have set it up to share my connection and extend it so i can use my xbox online. but from time to time it drops out and although it shows a green status light it will not be connected. However, when i unplug the express my macbook hops right back on the network and off i go again. i have to reset the express each time this happens or i cannot see it in the airport utility. added to this when my sister was home she could hop onto the wireless networt but when the express was plugged in she was not able to use the wireless other than in the room with the base station. any ideas cos its startin to get annoying!
thanks.

Mine does the same thing. I've had it for 3 months and its VERY frustrating...

My problem exactly. Anyone found a solution?