If you have FD7 installed on your Windows computer and you install FD8, your FDX files may be erroneously associated with FD7 and you will receive an error message about an unsexpected file format or the file not being compatible with this version of Final Draft.
To remedy this problem, uninstall both FD7 and FD8, then reinstall FD8. On Windows 8, simply type "Control Panel" (without quotes) to reach the Control Panel, and from there choose Programs and Features; on Windows 7/Vista, go to Start > Control Panel > Programs > Uninstall a Program and on Windows XP go to Start > Control Panel > Add/Remove a Program.
There is no reason to keep FD7 on a computer that also has FD8.
If you need to re-download the installer for FD8, it's here: http://kb.finaldraft.com/article/1001/79925/final-draft-8
IMPORTANT: Live technical support (phone, chat, email) for Final Draft 8 has been discontinued. You will still be able to find information and solutions in this knowledge base and in the FD8 User Guide.