Q: Problems with Airplay

I've just purchased two AirPort Express, installed them and they appeared in the Airport Utility (latest version) but after a few minutes they disappear and the only option I get is to forget them.  In that five minutes I can sleect them in Itunes, but if I deselect them I don't get the option to reconnect - error 15006 and the multiple speaker option disappears from Itunes.  After 10 minutes they both reappear in the Airport Utility and in Itunes, then disappear after a few minutes etc.etc...

Both AE are currently sitting 2 feet away from my router

Router is running in WPA/WPA2 mode

I have updated the firmware on them both - no difference

I have given them static IP addresses

Turned off IPv6

Only way I can see them both in itunes multi speaker with volume pop-up is if I name them exactly as itunes sees them Base Station xxxxxx, otherwise I can select them individually from the dock symbol

I have a new iMac running Lion 10.7.3 - HELP!