Resolved ZeroAccess trojan messages from McAfee and web browser failures

I am looking for assistance in removing malware that has infected my system. I am running Windows XP Home Edition Version 2002 SP3.

In the last week or two, I have noticed a bit of a drag on my system performance and my web browsers have occasionally been locking up (Mozilla Firefox) or closing by themselves (MS Internet Explorer). Yesterday I ran a full scan using McAfee, and the results showed that several viruses/Trojans were removed or quarantined. I also ran a full scan using Malwarebytes Ant-Malware. Malwarebytes did not find any problems.

After running those scans, a McAfee "Trojan Removed" notification message pops up several times an hour saying that "McAfee detected and automatically removed a Trojan from your PC. No further action is required." There is a 'More' link on these pop-up messages and when I click that, it always identifies the trojan name as "ZeroAccess ". The file referenced on the 'More' message identifying where the trojan was quarantined from is always in the C:\Windows\system32 folder, but the file name is different on each instance of the notification. Today, I ran a McAfee scan just on the C:\Windows\system32 folder and it did not identify any problems.

I addition to the recurring McAfee notification pop-ups, my web browsers are still periodically locking or automatically closing. Sometimes the entire laptop locks up and I have to reboot.

Any help that can be provided to troubleshoot and resolve these issues would be much appreciated.

Thanks.