What Chris said. I haven't seen that issue on my end, and can't replicate it now. See if you can replicate it with different browsers (IE, Chrome, the newer FF). If it happens in one but not in others, it's highly unlikely (but not impossible) there is something going on with the server side.
Here's what Mozilla recommends about that particular error message:
https://support.mozilla.org/en-US/kb...and-fix-errors