Live Update - Not Available

Hi,  I'm running NIS 2011 using Firefox as Internet Explorer kept crashing.  I cannor run live updated as I get the message it is not available.  This only happened 3 days ago.  I click One click support and my My PC installs updates then I have to restore my computer as it crashes too.  Can anyone help me out as it says my PC is at risk from viruses.  Thanks Lummox