Looks like it's actually a JavaScript problem.
Being that Firefox is a much more up-to-date and sophisticated program than the current release of I.E., I would expect it to be better than I.E. at reading JavaScript. What's interesting is that it is reading at least part of the script, because it's hiding the button in the first place. (The way I wrote the code, the button is actually visible before Javascript takes effect, so if somebody has a browser that can't read JavaScript at all, the button will show up). For some reason, Firefox is reading the code that hides the button, but it won't read the script that UN-hides it. And the code for each is nearly identical. So I'm stumped.
I did make one small tweak tonight that *might* make the difference. Try it again now and see if it helped. If so, problem solved. If not, I'll have to consult a JavaScript expert.
Regards,
Jonathan