Tab Mix Plus extension has compatibility issues with Firefox 17, you shouldn’t use it, so disable it right now.  If you’re using popular Tab Mix Plus Extension in recently released Firefox 17 then you may’ve already facing issues with add-on as it is breaking Firefox menu items and links. Mozilla has identified the issue and recommends affected users to either disable the add-on for now until new version is released in AMO or try the development version if you can’t live without it.

Tab Mix Plus is incompatible with Firefox 17, don’t use it 

Mozilla confirms the extension causing issues is not compatible with latest version of Firefox (although all add-ons installed from AMO should be compatible by default) and broken due to a bug.

‘The popular Tab Mix Plus extension is causing some problems for users in Firefox 17. The problems include broken menu items – like the one that opens the Add-ons Manager – and broken links in Firefox windows, like the About dialog.” Mozilla’s Jorge said in add-ons blog.

“This extension broke due to bug 761723, and a fixed version hasn’t been released to AMO yet. Apparently there’s a development version of Tab Mix Plus that fixes these issues, so hopefully it will be pushed to the general public soon.”

When next version of Tab Mix Plus is going to be available in AMO? Can I still use the add-on in Firefox 17?

Let me tell you next version of Tab Mix Plus update will happen in January 2013, if you can’t wait till then you can download dev. version which has fixes for these issues from this link (should be the first one).