If it works in Windows-XP but not Windows-7 I would guess the Font file has a fault that XP tolerates.
It seems to me that softy has limited documentation that hasn't been maintained recently, it's web page talks about nothing later than Windows NT.
It runs under Windows (3.1, 95, 98, NT), and requires a 386 or better.
This makes me wonder if the author has perhaps not tested it on Windows 7 - perhaps there is some quirk of Windows-7 that the author has not accommodated? Perhaps softy has some quirk that needs to be dealt with by the developer?
TTF file format
Perhaps there is an issue in the TTF cmap table for your font.
The ‘cmap’ table consists of a set of mapping subtables for different technologies and architectures.
Each mapping subtable has two numbers associated with it: the platform id and the encoding id.
It might be useful to check this.
I would try opening your TTF file in another editor such as FontForge - perhaps it will identify some problem?