I always skip the Launcher.exe, and use the KSP.exe to start the game. One way to "solve" the launcher problem when it is stuck in: "Checking for Updates" is to rename the "patcher.exe". WARNING, this will NOT update the 0.9 version to 1.0, for that you need to reinstall the game. When I reinstalled the game i removed the launcher shortcut from the desctop and added a shortcut for the KSP.exe