I was able to use my limewire yesterday, and today I have the never connecting issue. So I went and bought pro. Now I am still unable to connect.
Nothing has changed on my system.
Windows XP SP2
1 gig of ram
plenty of hard drive space.

I know that isn't a lot of info but as I said it worked fine yesterday. Nothing has changed, not my router or any of my system settings.

I have tried all the fixes previously listed. The only thing that may have changed is that Microsoft Malicious software update. But I don't know how to undo it.