Try the Firefox Safe Mode to see how it works there. The Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open the Firefox 4.0+ Safe Mode by holding the Shift key when you use the Firefox desktop or Start menu shortcut.
• Or use the Help menu item and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Don't select anything right now, just use "Continue in Safe Mode." To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before using the Firefox shortcut (without the Shift key) to open it again. If it is good in the Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one.

Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

Do you have a dictionary installed and selected?

You can see which dictionary is selected if you right-click in a text area and open the Languages submenu.

• Open the "Add Dictionaries" link to install a dictionary if you do not have one.
• Make sure that [X] "Check Spelling" in the right-click context menu is check-marked.

You can enable or disable spell checking globally:

• Tools > Options > Advanced : General: Browsing: "Check my spelling as I type"

You can look here for dictionaries:

• https://addons.mozilla.org/firefox/language-tools/

I reloaded FF15 and the underlining is over but the addons seem to still not be working. To open multiple tabs like this is in, I can't go to a previous tab like I could in FF14. I can't use the no script also. I can't say to allow the scripts on a page.