Hmm...not sure when these crashes started happening...a couple weeks I'm sure. Maybe when I started playing on a KAI LMS server? In fact, just to replicate the error, I played there again and got a different error:
Here's the bottom part of the log file that deals with it:
ScriptLog: Team 255
ScriptLog: Login: Tempest
Log: Possessed PlayerPawn: TMale2 Entry.TMale7
Init: Initialized moving brush tracker for Level DM-Agony.MyLevel
DevAudio: Galaxy SetViewport: WindowsViewport0
Log: Possessed PlayerPawn: bbTMale2 DM-Agony.bbTMale1
ScriptLog: SplashNotify:

reBeginPlay()
ScriptLog: SplashNotify:

ostNetBeginPlay()
Log: Attempting to record demo e:\utdemos\3-7_18-09-11_DM-Agony.dem
DevMusic: Load music: Music Course.Course
ScriptLog: SplashNotify::SpawnNotification(1)
ScriptLog: SplashNotify::SpawnNotification(2)
ScriptLog: SplashNotify::SpawnNotification(3)
ScriptLog: SplashNotify::SpawnNotification(4)
ScriptLog: SplashNotify::SpawnNotification(5)
ScriptLog: SplashNotify::SpawnNotification(6)
ScriptLog: SplashNotify::SpawnNotification(7)
ScriptLog: SplashNotify::SpawnNotification(8)
Log: 5596 18 0% 0 932 0 3 0 6 0 0
Log: 6391 18 0% 5176 4407 31 23 11 14 0 0
Log: 6391 18 0% 0 3762 0 61 0 59 0 0
Log: FactoryCreateText: TextBuffer with TextBufferFactory (0 1 NPLoaderLL_v16b.u)
Log: Execing NPLoaderLL_v16b.u
Log: FactoryCreateText: TextBuffer with TextBufferFactory (0 1 NPLoaderLL_v16b.dll)
Log: Execing NPLoaderLL_v16b.dll
ScriptLog: [NPLoaderv16b] [File] NPLoaderLL_v16b.dll [Installed] Yes [Loaded] Yes
Log: FileSize of file ACEv08g_C.dll: 1110016 bytes
ScriptLog: [NPLoaderv16b] [File] ACEv08g_C.dll [Installed] Yes [Loaded] Yes
ScriptLog: [NPLoaderv16b] Loading complete
Log: 1503 18 0% 628 6133 7 91 2 87 0 0
Log: 1503 18 0% 0 6400 0 90 0 87 0 0
Log: 1712 18 0% 817 6256 6 94 2 93 0 0
Log: 1712 18 0% 0 5934 0 95 0 93 0 0
Log: 1712 18 0% 0 6135 0 94 0 92 0 0
Log: 1712 18 0% 0 6196 0 94 0 93 0 0
Log: 1712 18 0% 0 6125 0 95 0 93 0 0
Log: 1712 18 0% 0 6140 0 94 0 92 0 0
Log: 1712 18 0% 0 6204 0 94 0 93 0 0
Log: 1712 18 0% 0 6182 0 95 0 93 0 0
Critical: appError called:
Critical: Assertion failed: Channel [File:C:\UTDev\Engine\Src\UnLevTic.cpp] [Line: 780]
Critical: Windows GetLastError: The operation completed successfully. (0)
Exit: Executing UObject::StaticShutdownAfterError
Exit: Executing UWindowsClient::ShutdownAfterError
Exit: UGalaxyAudioSubsystem::ShutdownAfterError
Log: DirectDraw End Mode
Exit: UOpenGLRenderDevice::ShutdownAfterError
Critical: ULevel::TickDemo
Critical: UpdatePostDemoRec
Critical: ULevel::Tick
Critical: (NetMode=3)
Critical: TickLevel
Critical: UGameEngine::Tick
Critical: UpdateWorld
Critical: MainLoop
Exit: Exiting.
Uninitialized: Name subsystem shut down
Uninitialized: Log file closed, 03/07/13 18:11:55