If you are infected with the "adnow" virus, you probably have these symptoms:

Internet searches are redirected to abnow.com, mediashifting or any other websites.
The antivirus protection detects Trj/Sirefef and/or Rootkit/ZAccess.

Panda Security has created a disinfection tool that should erase all traces of the virus.

Follow these simple instructions:

1: Download the yorkyt.exe disinfection tool.
2: Save the file to your hard disk; to the Windows Desktop, for example.
3: Double click the yorkyt.exe file.
4: A reboot will be requested to install a driver.
5: Another reboot will be requested to complete the disinfection.
6: When the disinfection is completed, accept the message that will be displayed.
7: To ensure a full cleanup, run a scan of your PC with the antivirus installed.