Program Control Setting question

Let me start by saying still planning to get NIS2010, just not financially able to now. Don't want NAV2010 upgradeI come here because this is the beast place on the net to get helpful adviceOk I had posted a question similar in nature to the one I'm about to post. But it IS a different question, so those who may wish to help me, please read through.

Currently NAV2008  on Vista OS. Single PC with Printer hooked to DSL modem ( Modem does NOT have a router). Modem connects to phone wall outlet. Whenever I turn on my computer, it is connected to the internet

I had concerns before about if I should block or allow the program Microsoft Local Security Authority Shell

(lsass.exe) to be able to access my network resources. I had set it at BLOCK (there is no auto option, only allow and block)But for some reason it is concerning me again as to which option to choose

Anyway, I thought someone on the forums ( a forum respected regular) had told me that you can remove a program from the program control/program rules portion of the firewall settings(control inbound access to programs on computer), and if it is needed it will come back.

I experimented and tried that with the services.exe program, removing it. Upon reboot the program returned to the list of programs in Program Control. So I decided to try this with the program Microsoft Local Security Authority Shell (lsass.exe)

So I went to NAV Protection Center and under

Options>Realtime Protection>Internet Worm Protection>Program Control> Program Rules

I found Microsoft Local Security Authority Shell (lsass.exe) and removed it

 I then rebooted the computer.

 I checked Options>Realtime Protection>Internet Worm Protection>Program Control> Program Rules

But I did not see  Microsoft Local Security Authority Shell (lsass.exe) listed. I turned off the computer for an hour and after restart, again i did not see the program listed

Now I see lsass.exe in task manager Processes and then I see it is related to the service SamSs (Security Accounts manager) and that is running. So lsass.exe is on

So my questions-

1. Should Microsoft Local Security Authority Shell (lsass.exe) always be listed in Program Control portion?

2. Have I put my computer in security danger by not having Microsoft Local Security Authority Shell (lsass.exe) listed under program controls in Norton Internet Worm Protection settings?

3. Should I try to put Microsoft Local Security Authority Shell (lsass.exe) back on the list?

 

I am able to log on my computer without issue and use my Printer. Access the internet.  

I appreciate all help in this matter. Thanks in advance