Configuring Salesforce Chatter with an account in an org that doesn't have Chatter enabled results in an unusable app. Upon start-up, it authenticates against the org, shows an error, "Chatter is not enabled for this organization", then exits.
To restore Chatter to a state where it prompts for the org type, Default or Sandbox, I had to remove the Encrypted Local Store used by AIR apps.
$ rm -rf ~/.appdata/Adobe/AIR/ELS/sfdc-desktop.*
The state is that great fiction by which everyone tries to live at the expense of everyone else. - Frederic Bastiat