I used DejaVu as the starting point for my version — Verajja Serif.
In FontCreator 6 the Preferred Family Name (Windows only) field is blank, but I am told by the creators of DejaVu Serif that the Preferred Family Name is DejaVu Serif, which may cause a conflict.
verajja-serif.png
If I enter a Font Family name (Verajja Serif) in this field will it solve the problem, and is this a bug?
The attached version is “Version 1.20 January 4, 2010” while the image shows version 1. Maybe that version contained “DejaVu Serif” in one or more naming fields, but your attached font is free of that 
The updated version 1.2 apparently still suffers from the same problem. I updated it after receiving the report. Do you recognise which program the screen shot is from?
There are no traces of “DejaVu Serif” inside your attached font file, except within the Copyright Notice naming fields. I suspect they forgot to uninstall your previous version.
Btw the Description namings fields are not the same with the Macintosh Roman and Windows Unicode BMP platforms.