spmcc123,
I assume there's a difference in OS versions, that would almost certainly affect it. And perhaps the hardware itself is playing a role in scanning?
1.)
PowerBook G4 1GHz PowerPC / Wireless Card Type: AirPort / Wireless Card Firmware Version: 9.5.2
When booted from a Mac OS X 10.4.11 or a 10.5.8 volume, and when clicking the AirPort icon in the menu bar, the only items displayed are:
• AirPort: On
• Turn AirPort Off
The PowerBook G4 never reports "Scanning..." or "Looking for Networks..."
2.)
MacBook Pro 2.4 GHz Intel Core 2 Duo / Card Type: AirPort Extreme / Firmware Version: Broadcom BCM43xx 1.0 (5.10.91.27)
When booted from a Mac OS X 10.5.8 volume, the initial list reads:
• AirPort: Scanning...
and then changes to
• AirPort: On
There are no changes after this.
When booted from a Mac OS X 10.6.4 volume, approximately every six - eight seconds, the list alternates between:
• AirPort: on
• AirPort: Looking for Networks...
Clicking on the AirPort icon invokes the scanning / search for networks. The difference for me seems to be hardware.
[edit to insert]
And operating systems – Leopard and Snow Leopard.