I found this on Malwarebytes Forum:

Posted 15 April 2011 - 01:07 AM
Hi and welcome to Malwarebytes.

A Zbot detection is a backdoor trojan. A backdoor severely compromises system integrity.

A compromised system may allow illicit network connections, disabling of security software, modifying critical system files and collection and transmiission of personal identifiable information without your consent.

I recommend that you disconnect this PC from the Internet immediately, and only reconnect to download any tools that are required. If you do any banking or other financial transactions on the PC or it if it contains any other sensitive information, please get to a known clean computer and change all passwords where applicable, and it would be wise to contact those same financial institutions to apprise them of your situation.

Though the Trojan has been identified and can be killed, because of it's backdoor functionality, your PC is very likely compromised and there is no way to be sure your computer can ever again be trusted. Many experts in the security community believe that once infected with this type of Trojan, the best course of action would be a reformat and reinstall of the OS. If it were on my PC I would not hesitate for a moment to do so. Please read these for more information:

How Do I Handle Possible Identify Theft, Internet Fraud and CC Fraud?

When Should I Format, How Should I Reinstall

Should you decide not to follow that advice, we will of course do our best to clean the computer of any infections that we can see but, as I already stated, we can in no way guarantee it to be trustworthy.

Should you have any questions, please feel free to ask.

Let me know what you decide.
Chris Fistonich
Consumer Support Specialist