I just bought a NEW computer (new HDD, new mainboard, new GPU...basically everything is new) yesterday and after installing zone alarm internet security suite, Zone Alarm detected a Trojan named "Trojan-Clicker.Win32.Wistler.a". NO external HDD or thumbdrive was inserted at all before the trojan was detected.
Zone alarm was unable to quarantine it or delete it on reboot or instantly.
Currently have not spotted any harm from this virus as the comp is new and fast.
never heard of such a false positive. if you google it you will find a lot of references of this malware and it is very difficult to remove. Do you have original OS disk? Than reformat at low level and reinstall, I am sure it will be gone.
I would suggest you get free help from bleepingcomputer or spywarehammer malware expert to remove it. See here below for the link:
Malware Clean-up Guidance