Karl, thanks for your advice. I finally was able to get rip of this trojan for good. I used the spybot before but did not update the detection, that was why it did not detect and delete the inforstealer trojan. Yesterday after I update the spybot software and run the search and destroy again, it eliminate this trojan permanently.
I really need help. For the past 2 weeks my computer is infected by a trojan call Infostealer in the Registry (hkey_Current_User\software\microsoft\internet explore\main)and only my freedom security anti-spyware caught and delete this trojan. My AdWare, spybot , Mcafee antispyware and even yahoo antispy software did not detect it. My freedom security antispyware delete it but it always came back everytime when I do the following : when I go to internet explorer, selcect tools internet options then content then autocomplete setting and when I uncheck the box for user names & passwords