Hello,
What Version of SEP 12.1 are you running? What Operating System is the SEP 12.1 installed on?
Error code 1835 usually indicates a delay or that a firewall / other network device is preventing timely communication with the LiveUpdate source server. Is there are firewall between this Win7 machine and the Internet?
More detailed information about why LiveUpdate is failing can be found in the following log file:
These are found under:
C:\Documents and Settings\All Users\Application Data\Symantec\LiveUpdate\Log.LiveUpdate
C:\Documents and Settings\All Users\Application Data\Symantec\Symantec Endpoint Protection\12.1.671.4971.105\Data\Lue\Logs
On Windows Vista, Windows 7, and Windows Server 2008:
C:\Program Data\Symantec\Symantec Endpoint Protection\<silo_id>\Data\Lue\Logs
Hope that helps!!