Réinstallé le jeu n'a rien changé, par contre j'ai découvert ceci.
C'est un bloc note qui se créer lorsque je tente de lancer LOL.
--- Log started at Mon Aug 01 18:17:01 2011
000000.000| 8780.0000kb| 8780.0000kb added| NONE| RADS::API::Impl::Main::Main: User kernel is not running, proceeding without that functionality.
000000.000| 8872.0000kb| 92.0000kb added| DEBUG| RADS::Common::RegistryHelp::RegKeyValueString::RegKeyValueString: (Software\Riot Games\RADS, LocalRootFolder, c:\rads)
000000.000| 8880.0000kb| 8.0000kb added| DEBUG| RADS::Common::SolutionManifest::Load: ("C:/Riot Games/League of Legends/RADS/solutions/lol_game_client_sln/releases/0.0.0.63/solutionmanifest")
000000.001| 8904.0000kb| 24.0000kb added| DEBUG| RADS::Common::SolutionManifest::Load: Succeeded
000000.001| 8904.0000kb| 0.0000kb added| DEBUG| RADS::Common::ConfigurationManifest::Load: ("C:/Riot Games/League of Legends/RADS/solutions/lol_game_client_sln/releases/0.0.0.63/configurationmanifest")
000000.002| 8904.0000kb| 0.0000kb added| DEBUG| RADS::Common::ReleaseManifest::Load: ("C:/Riot Games/League of Legends/RADS/projects/lol_game_client_en_gb/releases/0.0.0.24/releasemanifest")
000000.002| 8904.0000kb| 0.0000kb added| ERROR| RADS::Common::ReleaseManifest::Load: Failed to open "C:/Riot Games/League of Legends/RADS/projects/lol_game_client_en_gb/releases/0.0.0.24/releasemanifest".
000000.002| 8904.0000kb| 0.0000kb added| ERROR| RADS::API::Impl::RuntimeEnvironment::RuntimeEnvironment: Failure to load manifest "C:/Riot Games/League of Legends/RADS/projects/lol_game_client_en_gb/releases/0.0.0.24/releasemanifest".
000000.002| 8904.0000kb| 0.0000kb added| DEBUG| RADS::API::Impl::RuntimeEnvironment::GenerateFileMap: start building file map
000000.002| 8904.0000kb| 0.0000kb added| DEBUG| RADS::API::Impl::RuntimeEnvironment::GenerateFileMap: done building file map
000000.002| 8904.0000kb| 0.0000kb added| NONE| RADS::API::Impl::Main::Main: Could not determine solution or project runtime environment, execution will continue but all files will be treated as unmanaged in the current folder.
000000.028| 27216.0000kb| 18312.0000kb added| WARN| r3dFileImpl: Can't open Data\Spells\SpellMetaData.txt (from file r3dIFStream:

pen)
000000.029| 27216.0000kb| 0.0000kb added| ERROR| Failed to open "Data\Spells\SpellMetaData.txt"
000000.029| 27216.0000kb| 0.0000kb added| ERROR| Can't open input file Data\Spells\SpellMetaData.txt
000000.029| 27292.0000kb| 76.0000kb added| ALWAYS| OS Version String: Microsoft Service Pack 1 (build 7601)
000000.029| 27304.0000kb| 12.0000kb added| ALWAYS| Measured processor speed: 2269
000000.029| 27304.0000kb| 0.0000kb added| ALWAYS| CPU: GenuineIntel, Intel(R) Core(TM) i5 CPU M 430 @ 2.27GHz, Intel64 Family 6 Model 37 Stepping 2, 2261 (0 core)
000001.776| 31368.0000kb| 4064.0000kb added| ALWAYS| Display info: ATI Mobility Radeon HD 5650 2670 MB 8.14.0001.6099
000001.776| 31368.0000kb| 0.0000kb added| ALWAYS| Physical memory: 4294967296
000001.803| 48160.0000kb| 16792.0000kb added| ALWAYS| Global Log Level set to WARN
000001.804| 48160.0000kb| 0.0000kb added| ALWAYS| Build Version: Version 1.0.0.121 (Jul 7 2011/11:13:44) [PUBLIC]
000001.812| 48416.0000kb| 256.0000kb added| ALWAYS|
000001.813| 48444.0000kb| 28.0000kb added| ERROR| Failed to extract information from comandline string for normal game mode
La dernière ligne semble être l'origine du problème, mais je ne comprends pas trop ce que je peux y faire.