Not sure if this was solved yet... but just had same problem. I managed to fix it by installing a file search tool (Everything by Void Tools) and searching for "FontName .ttf". There's a space between the name and the extension (it pattern matches).
There was an additional ttf installed that had the typeface name followed by a "_0" (or was it an _1 ?). It's as if windows had installed two copies of the font. It was in C:/Users/Username/AppData/Local/Microsoft/Windows/Fonts".
It gave me the 'in use by system' warning, but a reboot allowed me to delete it. For good measure I also searched the registry for the font file name and removed any entries. After this the font was removed properly and when I reinstalled the font again it showed up properly.