Hello,

Is the machine connected to Internet? Are the MAC clients Managed?

If Managed, check the Liveupdate Settings at SEPM and also check if the MAC is able to communicate to SEPM properly or not?

If Unmanaged, then to schedule a time to automatically update your virus definitions with LiveUpdate:

1. From the Applications folder, open the Symantec Solutions folder and select Symantec Scheduler. 
    
2. In the Symantec Scheduler window that appears, click New. 
    
3. From the window that appears, choose Product Update. 
    
4. In the text box, enter a name for the task, such as Update virus definitions daily . 
    
5. From the pull-down menu under "Choose a product to update", select Virus Definitions. 
    
6. From the pull-down menu next to "Set a Frequency", choose Daily. 
    
7. Using the text box and/or the up or down arrows, choose a time of day for the update. 
    
8. Click Save, and then close the window.

Also, Check this Article: Symantec Endpoint Protection for Macintosh Frequently Asked Questions

http://www.symantec.com/docs/TECH134203

Hope that helps!!

Hi Gwtdt,

Is there anything the is different on those rotten apples-?  For instance, do they go through a proxy and the others do not?  Are the ones with trouble updating subject to any special permissions, or connect via a slower link?

There is a liveupdate log which can provide more information on the exact nature of the failure.  The best way to view that (and other key details) is through the use of this tool:

Gathering information about Symantec products on a Macintosh using GatherSymantecInfo
Article: TECH134761   |  Created: 2010-01-08   |  Updated: 2012-01-03   | 
Article URL http://www.symantec.com/docs/TECH134761

Please do keep this thread up-to-date with your progress!
 

Mick, all the problem Macs are in the same group as the rest and have the same policy. I'm not going through a proxy.

Mithun, thanks for the thread. I will dig around on these computer and update the sylink file to see if that will resolve the issue.

Thanks to both.

Hi Gwtdt,

Just a ping to check if you resolved your issue, and if there is and advice you can add to the thread that might benefit future admins in the same situation. 

Also: this recent article may be of help to those with Mac/proxy issues....

Configuring Proxy on a Mac for Live update.
https://www-secure.symantec.com/connect/articles/configuring-proxy-mac-live-update