hi ganges
This entire series of posts equates to a thread. The thread title is Nozzer. I hope that helps you to understand.

This is the best place to start for your problem: If LW 4 Will Not Connect (click on the blue link) & see at bottom of that post that if none of those suggestions solves your problem, then to post back with your system details.

It's my guess that if you've been using LW for a few years, your gnutella.net file might be out of date. Instructions in the above link about how to change it.