As the kba states, the issue is that the 8.0.8 update did not fully install -- this means that the virus detection engine won't run.
Is your version currently at 8.0.8.1?
If it's at 8.0.8, you can either run the update from the menu item to upgrade and fix the issue (if it's the one people have been experiencing with the 8.0.6 -> 8.0.8 upgrade), or uninstall Sophos, remove the Sophos plist preferences files, restart your computer and re-install Sophos. The upgrade is likely the easier path.
As the kba states, the issue is that the 8.0.8 update did not fully install -- this means that the virus detection engine won't run.
Is your version currently at 8.0.8.1?
If it's at 8.0.8, you can either run the update from the menu item to upgrade and fix the issue (if it's the one people have been experiencing with the 8.0.6 -> 8.0.8 upgrade), or uninstall Sophos, remove the Sophos plist preferences files, restart your computer and re-install Sophos. The upgrade is likely the easier path.