Hi,
Thank you for posting your query on Symantec community.
Internet connection is not mandatory to get rid of this message. I think SEP definitions are corrupted.
Firs try to repair the SEP client via add/remove programs.
If not helped then with the help of following article try to determine if definitions are corrupted or not.
Article: How to determine if virus definitions of Symantec Endpoint Protection client (SEP) 11 or 12 Small Business Edition, are corrupted
http://www.symantec.com/docs/TECH97677
If definitions are corrupted can clear them manually, following article can help you on this.
How to clear out definitions for a Symantec Endpoint Protection 12.1 client manually
http://www.symantec.com/docs/HOWTO59193
As a last attempt can install intellgent updater patch as well.