Just to check, you might try 
FrostWire or 
Phex to see if you have the same problems. 
I have heard in the past, some people who install FW then connect, then close it and LW suddenly works. 
Other than that, go to Tools > Options > Advanced > Performance and disable all options on this page. Then go to File menu choose Disconnect. Wait 2 mins, then go File menu, Connect.