Hi guys this is my first post and thread here and would like to back up what Jordan C has been saying.
I too have dowloaded FF2 from the Mozilla site and have run Spybot (The latest uptodate version) on a new laptop a few days back.
The scan picked up 4 adware items which Spybot consider potentially serious. When I clicked on the particular items on the Spybot report they all were listed as Firefox derived.
Whether these are false positives I don't know but they may well be similar to the Alexa / IE problems.
I am glad to see I'm not the only one who has found this problem.
In the mean time I'll stick with Opera!
