Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

• Don't make any changes on the Safe mode start window.

See:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

I have this problem, too. Also in safe mode. Windows XP, Firefox 4.0

Try:

• http://kb.mozillazine.org/Preferences_not_saved

This didn't help either. I also tried a fresh install of Firefox 4.0 (portable version) and the problem also exists: Tabs open at the end of the tab bar, not next to the current one - even though "browser.tabs.insertRelatedAfterCurrent" is set "true" as default.

I am pretty sure this is a bug in FF4. @cor-el: Are you sure this is working for you?(opening a new tab next to the current one instead of at the end of the tab bar)

Just to make sure we are talking about the same thing: When opening a hyperlink in a new tab, the tab opens next to the current like it's supposed to. But when I click "File -> New Tab" (or ctrl-t), the tab opens all the way to the right end of the tab-bar.