Issue:
When attempting to install the Symantec Endpoint Protection client onto a machine, the installation fails and rolls back around the point of registering with LiveUpdate.
Solution:
In the registry,
Find
HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders\AppData
value=%APPDATA%
and change it to
HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders\AppData
value=%USERPROFILE%\AppData\Roaming
Restart Windows 7 and then install SEP client again.
Source:http://www.symantec.com