I'm also having the same problem. I copied the last bit of my log, I think it might be saying that I have the same problem as everyone else:
Log: execGetAchievementCompleted Unlock10ofSideshowAchievementsCompleted=false
Log: OnPerkAvailable called - Notify=0 Type=2 Level=1
ScriptLog: STEAMSTATS: PostNetReceive called
ScriptLog: STEAMSTATS: CheckSideshowAchievementsCompleted 1 False 0
ScriptLog: STEAMSTATS: ServerSteamStatsAndAchievementsInitialized called
Log: Precaching: KF-WestLondon.LevelInfo0
Log: Static mesh batches: 14312520 vertex bytes, 2131668 index bytes
Log: Allocating 32768 byte dynamic index buffer.
Log: Allocating 65536 byte dynamic vertex buffer.
Log: Allocating 101696 byte dynamic vertex buffer.
Log: Allocating 112364 byte dynamic vertex buffer.
Log: Finished precaching geometry in 1.616 seconds
Log: Allocating 112672 byte dynamic vertex buffer.
Log: Finished precaching textures in 8.926 seconds
ScriptLog: START MATCH
ScriptLog: STEAMSTATS: PostNetReceive called
ScriptLog: STEAMSTATS: PostNetReceive called
Log: ALAudio: AL_OUT_OF_MEMORY in RegisterSound (generating streaming buffers)
Log: ALAudio: AL_INVALID_NAME in PlaySound END
Log: Unreal Call Stack: FALSoundSource::IsStopped <- FALSoundSource::IsFinished <- UAudioSubsystem::Update <- UALAudioSubsystem::Update <- UGameEngine:

raw <- USDLViewport::Repaint <- USDLClient::Tick <- ClientTick <- UGameEngine::Tick <- UpdateWorld <- MainLoop
Exit: Exiting.
Log: FileManager: Reading 1 GByte 673 MByte 782 KByte 412 Bytes from HD took 47.826233 seconds (30.127762 reading, 17.698469 seeking).
Log: FileManager: 0.000000 seconds spent with misc. duties
Uninitialized: Name subsystem shut down
Uninitialized: Allocation checking disabled
Uninitialized: Log file closed, Tue Jul 12 21:49:27 2011