If you are having issues with inSSIDer not scanning properly or throwing the "make sure you have selected a WiFi adapter, not an Ethernet adapter" error then follow the screenshots to help correct the problem.
I installed the inssider_0.1.1.1111_i386 (for Ubuntu 11.10).deb package
My Os is Kubuntu 11.10
When I run inssider, I obtain the GUI but I don't see the wifi adapter in the top right corner of Gui.
So, I think that my adapter is not compatible with inssider.
this is the output of lspci:
02:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8191SEvA Wireless LAN Controller (rev 10)
So, I complete my info with the shell's output when I run "inssider"
(inSSIDer:9080): Gtk-WARNING **: gtk_menu_attach_to_widget(): menu already attached to GtkMenuItem