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: All support for Final Draft 7, including software activation, has been discontinued. You may find solutions to problems in the online knowledge base or in the PDF manual found on the installation CD.