This only happens when you add the STV installer over this build, which is why no other STE reported it. Severity 1 for STV.

Version 5.0.0b21 (e285fa5f42d9) Pro
Wed, 21 Jan 2015 16:59:23 GMT
Branch: 5.0/release

Common errors reported in editor, probably related to materials.
1. "A typeload exception has occurred" appears frequentl, ~30x per build.
2. "TypeLoadException: Could not load type 'MaterialType'.
System.MonoType.GetMethodImpl (System.String name, BindingFlags bindingAttr, System.Reflection.Binder binder, CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[] modifiers) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System/MonoType.cs:213)
System.Type.GetMethod (System.String name, BindingFlags bindingAttr) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System/Type.cs:787)
UnityEditor.HostView.GetPaneMethod (System.String methodName, System.Object obj) (at C:/buildslave/unity/build/Editor/Mono/GUI/DockArea.cs:225)"