New Post: Once in a while the MEF container throws an activtion error

I have a problem that sometimes the MEF container throws a exception when starting the application.

Index was outside the bounds of the array.
at System.Collections.Generic.List1.Add(T item)
at System.ComponentModel.Composition.Hosting.ImportEngine.StartSatisfyingImports(PartManager partManager, AtomicComposition atomicComposition)
at System.ComponentModel.Composition.Hosting.ImportEngine.TrySatisfyImports(PartManager partManager, ComposablePart part, Boolean shouldTrackImports)
at System.ComponentModel.Composition.Hosting.ImportEngine.SatisfyImports(ComposablePart part)
at System.ComponentModel.Composition.Hosting.CompositionServices.GetExportedValueFromComposedPart(ImportEngine engine, ComposablePart part, ExportDefinition definition)
at System.ComponentModel.Composition.Hosting.CatalogExportProvider.GetExportedValue(CatalogPart part, ExportDefinition export, Boolean isSharedPart)
at System.ComponentModel.Composition.ExportServices.GetCastedExportedValue[T](Export export)
at System.ComponentModel.Composition.ExportServices.<>c__DisplayClass102.<CreateSemiStronglyTypedLazy>b__c()
at System.Lazy1.CreateValue()
at System.Lazy1.LazyInitValue()
at Microsoft.Practices.Prism.MefExtensions.MefServiceLocatorAdapter.DoGetInstance(Type serviceType, String key)
at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key) in c:\Projects\CommonServiceLocator\main\Microsoft.Practices.ServiceLocation\ServiceLocatorImplBase.cs:line 49

I have no idea where to start because it only happens somethime and it looks like the interface it's looking for in the container is not there. But it thinks it is.