I have a client that will not update it's defs beyond 7/2/2013.  Yesterday it was not reporting into the server and the SMC service would not start I had to replace the serdef.dat and cltdef.dat, it then reported in.  The TruScan Defs are up to date but the IPS and Virus defs are stuck at the same date.  There is enough drive space.

Last time I had a problem like this I uninstalled and reinstalled AV, is there a simpler less intrusive way of resolving this.  Currently there are 4 entries in the virus defs folder.

Try this

How to clear out corrupted definitions for a Symantec Endpoint Protection client manually

what did that start communicating. it might take some time.

try doing a repair from add/ remove programs once.

if you have internet access on client. 

try running the liveupdate manually

Check the Blog

Troubleshooting Articles for Repairing the Corrupted Definition

https://www-secure.symantec.com/connect/blogs/troubleshooting-articles-repairing-corrupted-definition