Hey guys,
i'm just getting started in udk, using the rift-version, and have encountered some strange crashes.
i managed to solve some of the issues, but one reproducable crash that i can't seem to get rid of still annoys me.

When i create a new level, set up a new terrain and open up the terrain modifier, i can create a new terrain setup layer and add a new terrain material.
but as soon as i want to delete it, it instantly crashes with a windows "BUILT WITH UDK"-error report popping up, telling me APPCRASH with code c0000005.

Log attached, hope anyone of you can help out and thanks in advance

Log: Log file open, 04/06/13 02:17:39
Init: WinSock: version 1.1 (2.2), MaxSocks=32767, MaxUdp=65467
DevConfig: GConfig::Find has loaded file: ..\..\Engine\Config\ConsoleVariables.ini
Init: Version: 10908
Init: Epic Internal: 0
Init: Compiled (64-bit): Mar 24 2013 16:42:13
Init: Changelist: 1583401
Init: Command line: editor
Init: Base directory: C:\UDK\UDK-2013-03\Binaries\Win64\
[0000.15] Init: Computer: x
[0000.15] Init: User: x
[0000.15] Init: CPU Page size=4096, Processors=4
[0000.15] Init: High frequency timer resolution =3.020537 MHz
[0000.15] Init: Memory total: Physical=8.0GB (8GB approx) Pagefile=16.0GB Virtual=8192.0GB
[0000.15] Log: Steam Client API Disabled!
[0000.17] Init: WinSock:x (192.168.2.3:0)
[0000.17] Init: Presizing for 0 objects not considered by GC, pre-allocating 0 bytes.
[0000.17] Init: Object subsystem initialized
[0000.17] Warning: Warning, Unknown language extension DEU. Defaulting to INT
[0000.17] Log: Last hardware survey: Ver=10908, Date=20130405. Uploading again.
[0001.54] Log: SystemSettings based on: SystemSettings
[0001.55] Log: Found D3D11 adapter 0: AMD Radeon HD 6800 Series
[0001.55] Log: Adapter has 1010MB of dedicated video memory, 0MB of dedicated system memory, and 3830MB of shared system memory
[0001.56] Log: Shader platform (RHI): PC-D3D-SM3
[0001.89] Log: PhysX GPU Support: DISABLED
[0001.89] Init: Initializing FaceFX...
[0001.89] Init: FaceFX 1.7.4 initialized.
[0003.28] Init: Finished loading startup packages in 1.28 seconds
[0003.28] Log: 82573 objects as part of root set at end of initial load.
[0003.28] Log: 0 out of 0 bytes used by permanent object pool.
[0003.33] Log: Supported Consoles:
[0003.33] Log: Mac
[0003.33] Log: PC
[0003.33] Log: Initializing Engine...
[0003.39] Log: Encountered missing default brush - spawning new one
[0003.40] Init: UEngine initialized
[0003.40] Log: Primary PhysX scene will be in software.
[0003.40] Log: Creating Primary PhysX Scene.
[0003.40] Init: Transaction tracking system initialized
[0003.41] Log: Can't find edit package 'OnlineSubsystemGameSpy'
[0003.41] Log: Can't find edit package 'OnlineSubsystemLive'
[0003.77] Log: Failed to upload UDK hardware survey to http://tempuri.org/PostUDKSurveyHandler.ashx in 3.59 seconds.
[0003.77] Init: XAudio2 using 'Lautsprecher (SB 5.1 VX)' : 2 channels at 48 kHz using 16 bits per sample (channel mask 0x3)
[0003.78] Init: XAudio2Device initialized.
[0003.83] Init: Client initialized
[0003.84] Init: Editor engine initialized
[0003.90] Log: Initializing Engine Completed
[0003.90] Log: >>>>>>>>>>>>>> Initial startup: 3.90s <<<<<<<<<<<<<<<
[0003.95] Cmd: MODE MAPEXT=udk
[0004.04] SourceControl: Source Control disabled in UDKEditorUserSettings.ini. [SourceControl] has Disabled=True
[0005.28] Log: Found D3D11 adapter 0: AMD Radeon HD 6800 Series
[0005.28] Log: Adapter has 1010MB of dedicated video memory, 0MB of dedicated system memory, and 3830MB of shared system memory
[0006.40] Cmd: MAP LOAD FILE="..\..\Engine\Content\Maps\Templates\Template _MidDay.umap" TEMPLATE=0
[0006.52] Log: Encountered missing default brush - spawning new one
[0006.70] Log: New File, Existing Package (Package Untitled_2, Package template_midday)
[0006.76] Log: -- Checking Building LODs
[0006.76] Log: Primary PhysX scene will be in software.
[0006.76] Log: Creating Primary PhysX Scene.
[0006.77] Log: Finished looking for orphan Actors (0.002 secs)
[0006.77] Cmd: MAP CHECKDEP DONTCLEARMESSAGES DONTDOSLOWREFCHECK
[0006.77] Log: TIMER ALL OF INIT : [4.868197]
[0016.75] Log: Increasing size of CachedMaterials to 1 for Terrain_0
[0018.38] Cmd: MODE TERRAINEDIT
[0025.00] Log: TerrainEditor: No block!
[0025.96] Log: New Layer
[0025.96] Log: Create Called for LAYER!
[0028.75] Log: Increasing size of CachedMaterials to 1 for Terrain_0
[0079.16] Log: TerrainEditor: No block!
[0083.65] Log: New Material
[0083.65] Log: Create Called for TERRAIN MATERIAL!
[0089.06] Log: AddSelected Material
[0092.07] Log: New Material
[0092.07] Log: Create Called for TERRAIN MATERIAL!
[0093.40] Log: Increasing size of CachedMaterials to 2 for Terrain_0
[0102.94] Log: TerrainEditor: No block!
[0114.32] Log: TerrainEditor: No block!
[0116.43] Log: AddSelected Material
[0139.91] Log: Increasing size of CachedMaterials to 1 for Terrain_0
[0143.42] Cmd: MODE CAMERAMOVE
[0145.30] Log:
==== Worlds needing PIE Save:
[0145.30] Log: Untitled_2
[0145.30] Log: ==== 1 total
[0145.34] Log: Built Phys StaticMesh Cache: 2.508 ms
[0145.34] Log: COOKEDPHYSICS: 0 TriMeshes (0.000000 KB), 2 Convex Hulls (2.164063 KB) - Total 2.164063 KB
[0145.51] Log: Save=166.780609
[0145.51] Log: Moving 'C:\UDK\UDK-2013-03\Binaries\Win64\..\..\UDKGame\Autosaves\UEDPIEUn titled_2_save.tmp' to 'C:\UDK\UDK-2013-03\Binaries\Win64\..\..\UDKGame\Autosaves\UEDPIEUn titled_2.udk'
[0145.56] Log: Save=52.123844
[0145.56] Log: Compressing '..\..\UDKGame\Content\LocalShaderCache-PC-D3D-SM3_save.tmp' to '..\..\UDKGame\Content\LocalShaderCache-PC-D3D-SM3.upk'
[0145.59] Cmd: MAP LOAD PLAYWORLD=1 FILE="C:\UDK\UDK-2013-03\Binaries\Win64\..\..\UDKGame\Autosaves\UEDPIEUn titled_2.udk"
[0145.70] Log: Finished looking for orphan Actors (0.003 secs)
[0145.70] Log: Game class is 'SimpleGame'
[0145.72] Log: Primary PhysX scene will be in software.
[0145.72] Log: Creating Primary PhysX Scene.
[0145.72] Log: Bringing World uedpieuntitled_2.TheWorld up for play (0) at 2013.04.06-02.20.05
[0145.72] Log: Bringing up level for play took: 0.005610
[0145.75] Log: PIE: play in editor start time for UEDPIEUntitled_2 0.533
[0145.75] ScriptWarning: Accessed None
SimplePawn uedpieuntitled_2.TheWorld:PersistentLevel.SimplePa wn_0
Function UDKBase.SimplePawn:TickSpecial:0088
.
.
.
.
[0148.64] ScriptWarning: Accessed None
SimplePawn uedpieuntitled_2.TheWorld:PersistentLevel.SimplePa wn_0
Function UDKBase.SimplePawn:TickSpecial:0088
[0148.68] Cmd: onrelease ShowMenu
[0148.77] Cmd: UpdateLandscapeSetup
[0151.01] Cmd: MODE TERRAINEDIT
[0154.90] Log: Delete
[0154.90] Log: OnDeleteSelected
[0163.06] Log: === Critical error: ===
Fatal error!

Address = 0x409c145a (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x409c1f31 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0xc41c33 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_vc_custom_64.dll]
Address = 0xc42373 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_vc_custom_64.dll]
Address = 0xc42430 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_vc_custom_64.dll]
Address = 0x8007d6f9 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x800d9a2c (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x801031f5 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x80106685 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x800bdc43 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x80104f56 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x76ea9bd1 (filename not found) [in C:\Windows\system32\USER32.dll]
Address = 0x76ea98da (filename not found) [in C:\Windows\system32\USER32.dll]
Address = 0x800fee03 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x80104b2b (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x40ce66a8 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x409c5207 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x40fb00c6 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x40fb38ad (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x40fb4c6f (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x40fb67e4 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x40b30afb (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x40c7122a (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x41018470 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x41018f09 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x800c533e (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x8000413e (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0xc5dc23 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_vc_custom_64.dll]
Address = 0x800d6cc4 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\wxmsw28u_core_vc_custom_64.dll]
Address = 0x4101d7cb (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x4101d88a (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0xf4d119c2 (filename not found) [in C:\Windows\Microsoft.NET\Framework64\v4.0.30319\cl r.dll]
Address = 0x1da861 (filename not found)
Address = 0x1 (filename not found)
Address = 0x3f900000 (filename not found) [in C:\UDK\UDK-2013-03\Binaries\Win64\UDK.exe]
Address = 0x38b14a0 (filename not found)
Address = 0xf4df6f39 (filename not found) [in C:\Windows\Microsoft.NET\Framework64\v4.0.30319\cl r.dll]
Address = 0x1 (filename not found)
Address = 0x77e9a0 (filename not found)
Address = 0x77e9a0 (filename not found)