If your PC is infected with a virus, the virus may disable your PC’s access to the anti-virus website so that it cannot update the latest virus definition file. You can access the intelligent updater as follows:

For Sophos Anti-virus:

1. Go to the URL http://www.sophos.com/downloads/ide/ 
2. Download the IDE files for your version of Sophos Anti-Virus you are running onto a CD or external storage device. 
3. Copy the IDE files to the Sophos Anti-Virus directory in your infected PC.
   (i.e. C:\Program Files\Sophos\Sophos Anti-Virus or C:\Program Files (x86)\Sophos\Sophos Anti-Virus). 
4. Reboot the computer. Sophos Anti-Virus will automatically recognise the new IDEs.