Hello,
Are the SAV 10 .x Clients Managed? Are these Updating from SSC?
Incase, this is an issue on few clients, try How to uninstall and reinstall LiveUpdate
http://www.symantec.com/docs/TECH101973
Are you running any Proxy on the Server?
If yes, then please try updating the SSC with the Latest Updates and check -
Updating virus definitions for Symantec AntiVirus Corporate Edition 10.x and Symantec Client Security 3.x
http://www.symantec.com/docs/TECH101198
A Quick Update for the SAV 10.x, it's Time to Migrate, check the Article below:
Be Aware: The Symantec Antivirus Corporate Edition 10.x and Symantec Client Security 3.x End of Support life is fast approaching!
https://www-secure.symantec.com/connect/forums/symantec-antivirus-10x-sav-will-reach-end-support-life-eosl-4-july-2012
Scan Engine Version information is unavailable in Symantec AntiVirus 10.x as viewed in the Product GUI or Symantec System Center
http://www.symantec.com/docs/TECH189026
Hope that helps!!