Alright. To really start out on this, I'd like to know your specs. Say how many files you share, how you connect.

If you're trying to download something rare, awaiting sources is a common occurance. What happens is this: you make a search, and someone returns a hit for the query. After this, many things can happen. That person can disconnect from the network, and if so, your source will be gone, and Limewire will wait for more sources. Also, the person who gave you the hit may not find that you are sharing enough files, and if so, they will become an invalid source, and then too you shall receive that message.

The key to avoiding all of this is to share files and try to find as many sources as possible. For instance, if you're searching for something and find few sources, try broadening your search by removing search terms. For instance, instead of "Bach Brandenburg Symphony#4 in G Major", try searching for "Brachenburg", which will most likely yield significantly more results.

I hope that helps you.