I had FontCreator 6.1 running and then entered my registration code.
I then saved the font I was working on. One glyph had been created from an image
Windows 7 x64
If you’re running FontCreator 6.1 then you’re entitled to a free upgrade to FontCreator 6.2, which is the latest version. I would suggest doing that first, then see if the problem occurs again. Help, Check for updates.