QCache crash when unlinking object if it is full

I am using the QCache container in the following context:

  QMutexLocker l(&mutex);

  static QCache<GatePort,MyLocalData> PortDrawingCache(10);

  MyLocalData* cachedInfo = PortDrawingCache[p];
  ....
  ....
  PortDrawingCache.insert(p,cachedInfo);

So it is used in a threaded environment, but all operations are protected using the QMutexLocker object.

However, on a rare basis i am getting a crash condition when inserting
The attached screen shot show the stack and data value. It can be nnoticed that the element that we currently try to remove from the hash is already no longer in it... so this looks weird.
Also n.p is obviously invalid pointer.