Rated 2 out of 5 stars

sorry but it's not working on startup (as I would like with Windows XP) my Portable Firefox 3.5.3 just minimizes for a little while then immediately appears on the desktop !
AW nothing new as I have been searching but never found a trick to minimize Firefox on startup !

This review is for a previous version of the add-on (1.2.1). 

Version 1.3.0 and above have the "Delay on start (ms)" option. Try to increase it and Firefox should remain minimized on startup.