Sorry for your problems. We haven't seen either of those glitches on any other computer so it is most likely your computer that is a little Bugged Out.
I'd believe that. Additionally, I won't judge you if you choose not to fix it. I've seen it before where it was a problem of Firefox handling the code differently than other browsers. Just making sure you're aware of the issue so you can choose to fix or warn people or whatever you choose to do with the information.