First of all, try to start Firefox in Diagnose Firefox issues using Troubleshoot Mode and disable all add-ons - you have quite a number of add-ons related to tabs, and some of these may be interfering with each other. When restarted, test if this has fixed the issue.

If solved, you can start turning your add-ons on again one by one, testing for each one that it still works, and by this method find out if a certain add-on causes this problem.

If disabling all add-ons didn't fix the problem, please see the article Home page with pipe character opens extra tabs when Firefox starts - this could also be an issue.

Please let us know how above works out, and if we can be of further assistance. Detailed feedback is appreciated and helps us to help you better, plus enables us to better help other users with similar problems.

If you use Delete browsing, search and download history on Firefox in Firefox 3.5/6 or Clear Private Data in Firefox 3 to clear the 'Browsing History' when Firefox is closed then restoring tabs from the last session (e.g. "Save & Quit" or "Show my windows and tabs from last time") doesn't work.