Consistent crashing while editing new maps

I seem to be suffering constant crashes. I can run all tutorials fine, but as soon as I attempt to start editing in a (practically) empty world, I get something like the following;

*[2014.04.22-21.29.08:229][ 30]LogWindows: Rendering thread exception: Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.0\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 518] Array index out of bounds: 14 from an array of size -572662307 Stack: Address = 0xeb16b496 (filename not found) [in C:\Program Files\Unreal Engine\4.0\Engine\Binaries\Win64\UE4Editor-Core.dll]*

Then a long list of other missing files, with this at the end;

*[2014.04.22-21.29.08:229][ 30]LogExit: Executing StaticShutdownAfterError [2014.04.22-21.29.08:237][ 30]LogPhysics:Warning: PHYSX: ..\..\PhysX\src\NpScene.cpp (2861) 8 : PxScene::unlockWrite() called without matching call to PxScene::lockWrite(), behaviour will be undefined. [2014.04.22-21.29.08:237][ 30]LogWindows: FPlatformMisc::RequestExit(1) [2014.04.22-21.29.08:237][ 30]Log file closed, 04/22/14 14:29:08*

I will note that my mainboard has had better days and I am only running on 4 of my 12Gb, it’s a hardware issue and intend to fix shortly. I’m just wondering if there could possibly be something else I’m doing wrong?