Try getting more space on your harddisk
Also try checking the box for incoming searches in your monitor window (even if you are connected as a leaf) worked for me
BTW I see lots of searches and that keeps limewire from disconnecting
Search for something even if you're not looking to download anything new. It helps Limewire stay connected. (especially when trying to connect)
Also if you have a lot of incomplete files, it's a good idea to delete the entire incomplete folder. Helps Limewire finds and continue the files you're downloading easier.