Anybody that has an idea what can cause this to happen? it work fine but we suddenly got this error

Message: This InitState method should not be called.
StackTrace:    at OpenAccessRuntime.ExceptionWrapper.Throw()
   at OpenAccessRuntime.DataObjects.InitState.copyFields(OID oid)
   at OpenAccessRuntime.DataObjects.PCStateMan.replaceApplicationPKFields()
   at OpenAccessRuntime.DataObjects.PCStateMan.setLoadRequiredIfNeededClearOrig()
   at OpenAccessRuntime.DataObjects.LocalPMCache.doMarkReloadNeeded()
   at OpenAccessRuntime.DataObjects.OpenAccessPersistenceManagerImp.beginCommon()
   at OpenAccessRuntime.DataObjects.OpenAccessPersistenceManagerImp.isResourceManagerEnlisted()
   at OpenAccessRuntime.DataObjects.OpenAccessQueryImp.ExecuteWithArrayImp(Int32 mode, Object[] parameters)
   at OpenAccessRuntime.QueryResultImpl.check()
   at OpenAccessRuntime.QueryResultImpl.GetEnumerator()
   at OpenAccessRuntime.QueryResultImpl.System.Collections.IEnumerable.GetEnumerator()
   at Telerik.OpenAccess.Query.ExpressionExecution.PerformDatabaseQueryMulti[T](Expression expr, ExecutionSettings settings, Object[] grpVals, Boolean checkOid, QueryOptions options)
   at Telerik.OpenAccess.Query.Piece`1.ExecuteMultiple()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at CSD4.ABI.Service.SqlWatcher.Implementation.Jobs.MF_12Close_OUT_MF_22c_OUT_Job.DoJob()

I think i found the solution, I had to allow multithreading on the Model

I think you've found the right solution. Whenever a context (or its managed objects) is accessed concurrently by different threads, the multi-threaded access needs to be enabled for the model. Otherwise there is no synchronization, potentially resulting in symptoms as described by you.

Regards,
Thomas
Telerik