Rarely the SkyGlass app preferences file gets corrupted which can cause the SkyGlass app to crash when launched. To fix this simply find and delete the SkyGlass app preference file. The next time you launch SkyGlass, the app will recreate a new prefs file and your app will be restored to the default state. Please note that you will lose all your prior setting and watchlist aircraft. If you have a watchlist, please see the additional FAQ on how to transfer your watchlist before you proceed. Please navigate to the following directory depending on your platform, and delete the following contents... Here is the path to the prefs file on Windows. Note you will need to "Show Hidden Files" to see the AppData folder.: This PC > Local Disk (C:) > Users > [ computer username ] > AppData > LocalLow > AviarLabs > SkyGlass > SkyGlass_psd.txt Here is the path to the prefs file on Mac: [Hard drive] > Users > [ computer username ] > Library > Application Support > AviarLabs > SkyGlass > SkyGlass_psd.txt After you delete the SkyGlass_psd.txt file, relaunch SkyGlass and you should be restored to the default state.