Re: Firefox will not allow me to close tabs or drag them to a new window.
You need to use the keyboard and open the File menu via Alt+F to see a Close Tab menu entry because some menu entries are hidden if you use the mouse.
Can you close a tab vi Ctrl+W?
Start Firefox in Troubleshoot Firefox issues using Safe Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).
Don't make any changes on the Safe mode start window.
I can often stop the scripts from Facebook, and then the tabs can still close; but if I stop TabBrowser.xml, tabs will no longer close. Unfortunately, when the FB scripts crash, I usually have little choice but to close the TabBrowser.xml script.
This now happens constantly while I use Firefox on Facebook. It no longer happens unless I am using Facebook, and is apparently unrelated to whether I play Farmville.