Look, let's start at the beginning here....
What problems are you having? Please describe them completely, when you have them, what are you doing when they occur? If there is an error message involved please give me the EXACT FULL wording of the error message. When did they begin? Had you installed any new hardware or software just prior to this?
You are giving us virtually NO information here.
a new file called AB221BD2.exe which has just showed up,
Just showed up WHERE?...on your desktop, your taskmanager, your email, in Programs...WHERE? Just saying a new file showed up tells us absolutely nothing.
You say you have used all the programs listed in the link...WHEN? Which programs? Where are the logs?
If they found nothing then why in the world to you believe you have a rootkit on the computer? There absolutely MUST BE A REASON that you feel you have one on the computer. You don't just run a "nifty program" for the heck of it, and if you do you are just looking for trouble somewhere down the line.
You also used the HJT version 2 Beta version, for now I would prefer to have you use the current version, 1.99.1, which is found on the link I gave you.
I am sorry, if you cannot or will not give full information requested that I personally cannot help you here. I have no idea what I am looking for or why I should be helping you look for a rootkit.