Shoutbox

Hi,
in the last days I installed Norton Internet Security 2007.
I noticed that every about 5 minutes more or less, Msn (and my browser Firefox) act as I'm not connected to the internet (I'm an Adsl user). So Msn disconnect itself (and Firefox can't navigate).
Also, sometimes happens that Msn (or Firefox) crashes without giving any error message... Simply shuts down, then I re-open it and may happen that, after some minutes, it shuts down once more... (sometimes happens that when I re-open Msn then it's Firefox that shuts down and viceversa)...
I'm searching for some help for how to correctly configurate my NIS 2007 in more than 1 forum, but anyone seems to have the same problem....
Please don't tell me to simply cut off NIS 2007
Or maybe I'm wrong: it ain't NIS fault, but I don't know...