Do some logs in NIS2010 automatically clear out?

NIS2010 17.8.0.5

Vista Home Premium 32 bit, Vista SP2

 

In NIS 2010, do some logs automatically "empty"?

I have last restarted my computer little over 3 days ago (Saturday 11/13/10). It has been left on since.

I notice in the NIS Security History, in the Firewall-Network and connections section there are no entries

There were entries on Saturday and Sunday. Do these entries just disappar after 3 days?

My other logs like recent history go back to Friday 11/12/10

 

Just wondering why the history in Firewall-Network and connections seems to vanaish after 3 days?

And no, I didi not accidentally hit the delete button