Do you ever write out
img or anchor tags manually using Firefox?
If you do, you've probably experienced this bug:
It writes an "x" in front of the
href attribute, breaking the link.
This was entered as a bug 9 months ago, then finally closed 2 weeks ago with a can't repro comment.
I just tried it with WP 2.0.4 and Firefox 2.0, and it's very alive.
I don't know how trac works, but if anyone has suggestions for getting this back on the front burner, please reply.