Available Networks and Signal Strength

I am using XP pro... the network icon in the try shows me connected with a
signal strength of "excellent" however, if I look in available networks
listing, it shows the same network as "no signal". I am broadcasting my
SSID, having swtiched from not broadcasting it in an attempt to resolve
this, and use WPA. Even the Wal-Mart, 1.5 miles away shows up with an
Excellent signal in my listings...

Any ideas as to why this is?

TIA,

Jeff