When there is an interface which defines an event within the assembly targeted by the InitializeEventHandlers aspect, compilation fails.
Unhandled exception (4.0.34.0, 32 bit, CLR 4.5, Release): System.NullReferenceException: Object reference not set to an instance of an object.
at PostSharp.Sdk.AspectInfrastructure.TypeInitializationManager.^nCElfVTrtpDd.^Dpi1V+WW(MethodDefDeclaration _0)
...
A current workaround is to exclude the particular event in question by using [InitializeEventHandlers( AttributeExclude = true)]. This does not seem the aspect from being applied to implementing classes.