07/15/2012 22:15 [INFO] Solid LauncherLib [1.0.0.33] initializing...
07/15/2012 22:15 [INFO] Add App[League of Legends Launcher] Exe[C:\Riot Games\League of Legends\lol.launcher.exe] to Windows Firewall
07/15/2012 22:15 [INFO] Retrieving dynamic path[http://l3cdn.riotgames.com/LOL.Produ...SourceURL.xml]
07/15/2012 22:15 [WARNING] Error retrieving [http://l3cdn.riotgames.com/LOL.Produ...SourceURL.xml] ErrorCode 404

League was working fine until I got a virus, than all the sudden the login screen wouldn't work. Now i'm getting this error.. Someone please help me!

trying deleting your lol_air_client. i deleted my lol files after the uninstall and it worked for me. hoped i helped.

I deleted all my lol files before the uninstall and than it worked! Yes you did help good sir!