If someone gave me a penny for the amount if times i have replies to a post regarding this same problem, i'd be a rich man.
The problem is simple, it is not yours, it's the new version of LimeWire's.
Even if you do eventually connect to the network you will get hardly any results anyway, which is another huge issue in LimeWire 5.0.
I have said to another few people today that the newest version of software is not always the best.
My advice is to go back to LimeWire 4.18, its faster and much more reliable.
Here is the link to download that version Download LimeWire Basic 4.18.8 - FileHippo.com
Hope this helps, my friend