Whenever I click on a tab and drag it to either the left or right in its original window or attempt to drag it so it's own its own browser window, I get the cursor along with the thumbnail of the tab I'm moving, but I can't drop it anywhere. The only way I can get back to functioning is to force-quit Firefox.
Re: Can't move tabs in Firefox 17.0.1 Mac OS 10.6.8
Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).
Do not click the Reset button on the Safe mode start window or otherwise make changes.