Hi,

       In this scenario I would suggest you to copy the sylink file to a shared location and then you can write a log on script wherein when the client logs in the smc service  stops then it looks for the required sylink file in the shared location  replaces it and then starts the smc service again. You can keep this script as long as all the clients do not report to the SEPM thereafter you can remove the script.

Hello! Please try disabling Windows Firewall and Simple File Sharing.

What is the server paltform u r using for SEPM???
U can deploy the upgrded version of SEP  i.e. MR5

For replacing the sylink remotely refer the below article and
download

How to run the
SYLINK REMOTE to Replace the Sylink Remotely

http://www.symantec.com/connect/articles/how-run-sylink-remote-replace-sylink-remotely

Sylink Remote

http://www.symantec.com/connect/downloads/sylink-remote

I think it is better to find out the reason first for not communicating

below article can help you in this

Troubleshooting
Client Communication

http://www.symantec.com/connect/articles/troubleshooting-client-commuincation

One more possibility for not communication is related to
firewalls

below doc can tell u which are the ports used by SEPM for
communication and assure all these ports are open

http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007090614430148