I have a similar problem in that the Chumby will no longer display any WLAN SSIDs. It used to work reasonably well (with the usual problems actually getting connected) but since tonight my WLAN doesn't even show up in the selection screen any longer, nor do the others in the vicinity. I didn't change anything on my WLAN router, and my laptop, which is sitting next to the Chumby, has no problems getting connected.
I do see the Chumby's MAC address on the WLAN selection screen, and if I plug in an USB WLAN dongle (an MSI US54SE II) and reboot the Chumby, nothing changes except that the dongle's MAC address is displayed instead of that of the Chumby's internal WLAN card. If I enter the correct SSID manually, the Chumby just sits there »Scanning for access point ...« and nothing happens.
What could be going on here?