Stationery files are not meant to be opened directly. To open a new document in one of these formats (i.e. Sitcom, Stageplay, Friends, etc.), open Final Draft, go to File > New. Select the format you want and it will open a new document in this format.
NOTE: Live support for Final Draft 7 has been discontinued. You will still be able to install, activate and use FD7 on appropriate computers but email, chat and telephone support is no longer available. Live activation assistance will be available via phone (818-789-6281) and email and chat (links on the left side of this page) until June 14, 2017.