Restart Computer After Update: Inconsistency

I have NIS 2011 (version 18.7.2.3) installed on 3 Windows XP-SP3 computers.  On 2 of the pc's I am sometimes asked to restart the pc after a Norton has performed an update, but on the 3rd computer I am never asked to do so.  I thought perhaps NIS had been configured a bit differently on the "odd man out" computer, but I walked through all the settings and they are identical across the 3 computers

 

Any idea why I might be seeing this discrepancy?  Could it indicate a problem (and potential vulnerabilities) with the NIS installation on the computer that never requests a restart?  Thanks.