It might be a pop-up window. Are there any other features missing, such as the full toolbar, scrollbars, etc.?

If you do not want sites to be able to strip the Bookmarks Toolbar (or other features) from pop-up windows, you can change some hidden settings:

(A) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(B) In the search box above the list, type or paste feat and pause while the list is filtered

(C) Assuming dom.disable_window_open_feature.personalbar has its default value of false, double-click it to switch the value to true

The other preferences that starts with dom.disable_window_open_feature. relate to other features. If you do not want sites to be able to strip them from popup windows, you can switch the ones currently set to false to true in the same way.

I did make the changes and restarted firefox, but it didn't fix the problem. What I ended up doing was opening a new window and moved all the tabs to it.

Thanks for trying. JT