Endpoint Protection

In our network few machines (clients) are not getting live update in Symantec Endpoint Client.Live update date is shown old. OS of that machines in MS 2000.Is there any different settings?..

Did you install client as managed or unmanaged... 
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If you have installed as manage
Check whether server is having latest update.

Check the communication between server and clients.
REF: https://www-secure.symantec.com/connect/articles/troubleshooting-client-commuincation  

Check Liveupdate policy in the SEPM. Check the GUP if assigned.
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If you have installed as umnaged.
  Check whether you are able to reach http://liveupdate.symantec.com form the clients.

  Check the proxy configuration if any.

Download intelligent updater and update. 
REF: htttp://www.symantec.com/business/security_response/definitions/download/detail.jsp?gid=savce
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AV and AS updates are regular but PTP and NTP updates are not released daily so you may find old date.

Latest version of SEP(RU5) is available try to upgrade.. Its very good....

I HAVE ALREADY GIVE SYLINK AND STOP SMC AND START AGAIN AND UPDATE THE CONTENT FROM SERVER SITE BUT STILL IT IS OUT OF DATE.I HAVE CHAECKED THE LOD IT UNABLE TO CONNECT LIVEUPDATE.I HAVE ALSO CHECKED THE CONNECTIVITY AND PROXY SETTINGS.PROBLEM IS STILL THERE. 

Check the logs in the clients.

Go to View Logs---> Client management---> System logs.

Check whether it is able to connect to SEPM. what is the error after that.

Reinstall LIveupdate and check....

 Your problem may be because of corrupted virus definition also try this
How to clear out corrupted definitions for a Symantec Endpoint Protection Client
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007123111551948
if after this also problem not getting solved try to reinstall live update
ref: http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007100907303548

Download intelligent updater and update client. If update status wont change than you may have to clear the corrupted virus definition.