Much less radical is just to use the command line options to create a new profile and see what happens. I have fixed obscure problems in firefox by blowing away

Much less radical is just to use the command line options to create a new profile and see what happens. I have fixed obscure problems in firefox by blowing away the profile. 99% of what I need is stored in firefox sync so it's an easy process to delete an old profile and sync back up. Sounds like OP wants to get to the bottom of this though as a haX0r-ng project.