Problem with LiveUpdate

Hello,

 

I am attempting to run a LiveUpdate, but I receive the following message when it completes:

 

Downloading Symantec Security Software (1 of 1), complete.

Installing Symantec Security Software (1 of 1), failed.

LU1821: This update failed because it tried to overwrite a file that was in use. Close all of your Symantec applications and run LiveUpdate again.

Installation failed, error summary...

LU1806: LiveUpdate downloaded all of the updates you requested, but all of them failed to install. Please try to get the updates at a later time.

LiveUpdate session is complete.

 

During the update there are no applications at all (Symantec or otherwise) that are active. Could someone please shed some light on this? Thanks.