Crash when no network connection (#90)

When there is no network connection available and SIM is configured to automatically check for updates, SIM.exe crashes on launch. I had to manually reset the configuration to AutoUpdateType "None" in my user-specific .config file to work around this. You should be able to handle any exceptions during the upgrade check (which occurs in the child process/thread that is spawned), and maybe update the status bar with a note that the update check failed (no dialog box, please :)).