Hi,

A collection is by default not thread safe, if you are enumerating a
collection you cannot add an element to it, it would rise an exception.

Take a look at skeet's singleton implementation to know how to do a thread
safe singleton class.

Of course this has nothing to do with making the collection operations
threadsafe. You have to do this by your own using some locking mechanism.

I would not implement the IBindingList  , what I would do in this case is
implement an event in your collection that is risen when a new element is
added to the collection, doing so will allow you to do whatever you want on
the interface.

The form hangs probably cause the worker thread is not done yet.

Hope this help