MacBook Pro not finding Airport Extreme Base Station

I'm running a 15" 2011 MacBook Pro with Lion 10.7.1. Recently added an Airport Extreme (5th Generation) to the network, and connection was a snap. But now, when I take the laptop with me when going out, I can't find the AEBS when I'm back in its range. Running AirPort utility will not turn up anything. Ironically, I can still acess the Internet, but cannot print to networked printers or see the AEBS. The only way I can resolve this is to restart the MacBook Pro and reset the PRAM. While this works, it's quite annoying. I have checked all network settings, and those appear OK. Any solutions?