Launch FF and click the link on Help>About screen to check for updates. Once the update installs, reboot the PC and see if it's fixed.

Some sites say you will need to uninstall FF and reinstall it...

Cant get on internet from firefox or  internet explorer -get a " cant load xpcom "  when i click on it.cant uninstall from control panel.  How do I  uninstall?

cant load xpcom "  when i click on it.

Do you mean when you click on the Check for Updates link in FF? In one thread I saw, clicking the update link still worked even though they got the xpcom error.

Does the account you're using have administrator privileges so you're allowed to uninstall things?

Try rebooting in safe mode (reboot and press F8) to see if you can uninstall that way. Or maybe download the free version of Revo Uninstaller on USB stick and install it on the one with the problem.

Tried downloading firefox to thumb drive to laptop-still get " can't load xpcom "

I click on firefox or internet explorer app i get "can't load xpcom. " computer is hooked up to wireless router & working

Have a read here and here.