The SEP Inst.log is a big file. If you are not able to paste the entire log then search for return value 3 and paste 5-6 lines above and below it.
Else try...
Try the step in sequence:
1.Uninstall Live update ( If it is there in Add Remove program)
2. Delete the following folders (if they exist):
C:\Program Files\Symantec
C:\Program Files\Symantec Antivirus
C:\Documents and Settings\All Users\Application Data\Symantec\LiveUpdate
3. Install LiveUpdate by running the following file from CD1: \SEP\LUSETUP.EXE
4. Install Symantec Endpoint Protection. from CD 1\SEP Folder\Setup.exe ( as an unmanged Client )
Follow the steps to make the Client managed
How to change a Symantec Endpoint Protection client from unmanaged to managed
1.Copy of the file Sylink.xml from the server from C:\Program Files\Symantec\Symantec Endpoint Protection Manager\data\outbox\agent\
2. On the client computer , click Start > Run, type smc -stop, and click OK.
3. Copy the Sylink.xml into the C:\Program Files\Symantec\Symantec Endpoint Protection folder, and replace any existing Sylink.xml file.
4. Click Start > Run, type smc -start, and click OK.