Try disabling Ultrapeer abilities. Go to LW's menu bar, Tools -> Options -> Advanced -> Performance & you will see the options. In fact you could disable all options on that page.

Are you always seeing a brick wall or only sometimes after LW has been on for a while. It's my guess your router's UPnP is losing communication with LW due to LW being busy for a long time or simply java having memory issues which is common.

After my LW has been on for perhaps 24 hours & it's been very busy over that period, it sometimes starts to show the brick wall. Even though there are people uploading from me. lol I will then usually do a restart, making sure I don't interfere with people's downloading from me, checking my library for uploads to check if they are almost finished or early on in downloading a file(s) from me, etc.