I take it you are using the method shown in the using the spell checker article. Do you get a context menu like the one in the attached image when you right-click on a spelling error?

If not, you may have an add-on that is causing the problem, try the procedure in the troubleshooting extensions and themes article.

No I get an edit menu. Your image is the menu I want!! I will troubleshoot as you advise. Thanks. I'll report back.

No good. Even in Safe Mode I get the edit menu when right clicking on a misspelled word. Any other ideas??

See also Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems for problems with toolbars that install as a plugin.

You can see which dictionary is selected if you right-click in a text area and open the Languages submenu.
Also make sure that [X]"Check Spelling" in the right-click context menu has a tick.
You can also try to toggle the "Check Spelling" item off and on again.

See:

• http://kb.mozillazine.org/Spell_checking
• How do I use the Firefox spell checker?