Why don't the tabs in Firefox close?

[Bookworm]

I have recently noticed some tabs in FF won't close when I click the "x". This has started rather recently, perhaps within the past few weeks. As far as I can tell, there is no pattern to what types of websites might be causing this. Sometimes I've opened up two tabs of the same site, and only one will close.

The only thing that seems to fix it is to close FF entirely and reopen a new session. I tried disabling all the add-ons to see if that would help, but it didn't work. Suggestions?

[Robert]

You can figure out for which websites you are facing this issue. While browsing some websites, there is some non-responsive codes will run. if you wait some time, you will get pop up box and asks for stop or wait. Once you click on stop button, you can easily navigate the tabs.