Firefox Error during Browsing..... Help

Have you tried updating Java and Firefox on your computer?

If updates don't work, you may need to uninstall and reinstall Firefox on your computer.

I think you should use another browser of re-install again your firefox.

It's also possible that you have gone to a site that has errors in its code.

This can be verified by going to the same exact site using a different computer. If the site fails on another computer, then you can be reasonably sure the problem is with the site, not with your computer.

If the site works on another computer, then you know the problem is on the computer you've been using. In that case, either try a different browser or follow the suggestions already given by others.

Finally, it nearly always is best to keep your operating system up-to-date. Quite commonly a system update will fix problems like this.