Firerfox not shutting down properly?

Hi

What windows version & service pack you using?

What version of Firefox, And is it latest update (help menu and about will tell you this)?

Start Firefox in its safe mode and see if it closes ok, by starting in Firefoxes safe mode you dont start and addons and it could be one of them csusing the issue, so if Firefox works ok then start it normally and disable all addons and themes and enable one at a time to try and trace the culprit.

Also check for updates to your addons

Do you get and error messages when it crashes, check Event Viewer for errors at time of crash for a faulting files names.

As a last course of action uninstall and reinstall, but with no addons to see if Firefox works ok, then add your fav addons back.