To add to Farzad's notes...
You can run LiveUpdate by simply doing Start > Run > LUALL > Ok.
For SEP, you need to run LiveUpdate version 3.3.
- LiveUpdate 3.4 and 3.5 are for other Symantec (Norton) products.
The LiveUpdate log is found in:
C:\ProgramData\Symantec\LiveUpdate
- Post the file called Log.LiveUpdate here and we can see if there's anything obvious.