Help needed to resolve Trojan Gen 2, Zeroaccess on Win7 64 bit machine

My PC was just infected by Trojan Gen 2 and Zeroaccess on July 14, most likely through Adobe Flash Player update alert. I have Semantec Endpoint Protection (SEP 11), which detected the threat, but couldn't fix it after a few SEP full scans. Here are the two files infected:

 

Desktop.ini              Trojan.Gen.2                         Access Denied                      File                        c:\\Windows\assembly\GAC_64

Desktop.ini              Trojan.Zeroaccess              Access Denied                      File                         c:\\Windows\assembly\GAC_32

 

 

Every 3 or 4 minutes, if the computer is connected to the network, a set of three files will be quarantined and/or deteted by the SEP. One of them is:

80000000.@        

 

My system is Windows 7 Home premium 64 bit, running SEP version 11. I see that many people here have successfully removed similar threats with help from Quads. So I am anxiously waiting for some help from Quads, and thank you in advance.

 

I have a USB stick drive.