• 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/

See also:

• http://kb.mozillazine.org/Spell_checking
• http://kb.mozillazine.org/Dictionaries
• https://support.mozilla.com/kb/Using+the+spell+checker

I am having this problem too since I updated to Firefox 8. I have Windows XP.

I have British English Dictionary 1.19.1 installed and enabled. I have 'Check my spelling as I type' enabled in Tools > Options > Advanced : General: Browsing.

When I right-click in a text box I do not have a Languages sub-menu, either active or greyed-out.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

I have the latest Firefox and only updated spellcheckers, for English, Russian, and Hebrew. At my home computer they work. Here at work they don't. Alll words in English are underlined red as though they were wrong, and Russian and Hebrew don't do a thing. Obviously I have activated the spellcheckers in the add ons menu, and I have the "Check my spelling as I type" option turned on.

Does "Check Spelling" in the right-click context menu of a text area have a check mark?

Is the correct spelling dictionary selected in the Languages sub-menu?

Yes and yes. I m a more experienced user. Th eproblem persits even as I write these words.

Eureka. I followed my instincts and it worked. My XP is in Russian. In the Regional and Language Options of the Control Panel I entered the Advanced settings and changed the Language for non-Unicode programs to Russian. Ever since, all my language spell-checkers work perfectly.