The Addon Manager Installer puts the file in C:\Windows by default.
No, it doesn't.
The Addon Manager installer puts the file in the correct folder for the OS used, which is C:\Windows ONLY under Windows XP
Under Vista and above, which includes Windows 7, the Addon Manager installer puts the .dll in the C:\ProgramData\Esellerate folder
I asked you to check, NOT because our installer puts the .dll in the wrong folder, but because you might have run installers for *other* products (including old Cloud9 installers) that use the C:\Windows folder, regardless of the OS, which is wrong.
Are you running the installer, or Windows 7 itself, or FS9, in one of the XP compatibility modes, or the XP Virtual machine ? This would explain why you have that .dll in the C:\Windows folder, since your system is behaving like XP.