I am on a fresh 3.1.3 install with no plugins active and my visual editor is disabled. This should never happen.
I already tried:
- deactivating all plugins to see if this resolves the problem. I don't have any plugins to deactivate.
- switching to the Twenty Ten theme to rule out any theme-specific problems. No luck.
- resetting the plugins folder by FTP or PhpMyAdmin. Sometimes, an apparently inactive plugin can still cause problems. No luck.
- If all else fails, manually upgrade. Download a fresh copy of the latest.zip file of 3.1 (top right on this page) to your computer, and use that to copy up. You may need to delete the wp-admin and wp-includes folders on your server. Read the Manual Update directions first! No Luck.