How do you stop Firefox Back, Forward, and Refresh buttons from becoming greyed/grayed out, and how to recover from it?
This is a well-known problem, a Google search quickly reveals hundreds of hits.
It's so common in fact, that it suffers from "question spam" -- it's IMPOSSIBLE to find the correct solution among all the thousands of postings. I am of course contributing to the problem by posting this now, but I hope SU's community moderated format will help uncover the real answer once and for all :-)
It happens in all operating systems - Linux, Vista, Windows7 are most commonly reported.
Reinstalling Firefox typically does not solve the problem.
It's not caused by any specific plug-in.
The solution involves removing some hard-to-find / elusive file.