Hello,
Which version of SEP 12.1 are you running?
Could you upgrade the IE 7 to IE 8 or above??
I would suggest you to Manually update the SEP Manager / SEP clients via .jdb file
How to update definitions for Symantec Endpoint Protection Manager (SEPM) using a .jdb file
http://www.symantec.com/docs/TECH102607
How to manually update definitions for a managed Symantec Endpoint Protection Client using the .jdb file
http://www.symantec.com/docs/TECH104363
OR
How to apply rapid release definitions to a Symantec Endpoint Protection (SEP) client.
http://www.symantec.com/docs/TECH104979
Another workaround is to reinstall the SEP client on this computer, preferably with the latest release of SEP 12.1 exported from the SEPM with current definitions.
One more is to reboot the affected computer and immediately running LiveUpdate (this LU session should then occur when contiguous space is at its maximum).
Hope that helps!!