Normally there is a champion in the background or as of last patch the summoners cup. Well that's gone and it has been replaced with a black background. The login box is still there so I can login, but when I do I just get a black screen. Also I can't close the league window by pressing X in the top right, I have to go into task manager.

Have you tried:
1. Try running as an admin by right clicking on the executable and selecting "Run As" and "Administrator", or by using the lol.admin.launcher.exe

2a. Delete everything inside the your RADS downloads folder (Default Path is, C:\Riot Games\League of Legends\RADS\downloads) AND
2b. Delete everything inside your RADS solutions folder ( Default Path is, C:\Riot Games\League of Legends\RADS\solutions)
2c. Restart your computer and repatch

3a. Delete the lol_air_client folder in your RADS projects folder (Default Path is, C:\Riot Games\League of Legends\RADS\projects) AND
3b. Delete the lol_air_client_config_na and the lol_launcher folders inside the RADS projects folder.
3c. Restart your computer and repatch

4a) Go to your Riot Games projects folder and open the folder with the number for the latest release (Default path is C:\Riot Games\League of Legends\RADS\projects\lol_air_client\releases\0.0. 0.###) Find the folder with the highest number (currently 0.0.0.176 as of 8/6/12)
4b) Delete the following files:

• releasemanifest
• S_OK

• lib (folder)
• ETA-INF (folder)
• mod (folder)
• lolclient.exe (file)
• lolclient.swf (file)
• locale.properties (file)

I got the same problem, was fine last night, but now, this happens