If a file is saved to the root of a drive ("MacintoshHD"), the open/save/save as commands stop working.
In TeleKast.js, add this as the second line of SaveScriptAsPrompt()
if(strDefaultFolder == "") strDefaultFolder = objDirUtils.getHomeDir();
This is a temporary work around. This problem needs to be addressed properly, and in multiple locations.
Another work-around (without having to change the source code): remove the Mozilla Preferences Service's preference file. On mac, this is located at: ~/Library/Application Support/TeleKast/Profiles/___.default/prefs.js