There was a problem with Tab Mix Plus and Firefox 17. In an effort to provide the best experience for our users, we chose to mark the add-on as incompatible. The Developer of Tab Mix Plus has since released an update that fixes the issue (version 0.4.0.3.1). Updating Tab Mix Plus fixes the issue.
If you haven't installed the dev build of Tab Mix Plus, you can simply update your Add-ons to install the latest version:
If you installed the Dev Version of Tab Mix Plus, you will have to remove it before installing the updated release.
Click the menu button and choose Add-ons. The Add-ons Manager tab will open.
Please read Find and install add-ons to add features to Firefox for further information.