Stop unwanted event handling for combo boxes

[Scott]

I'm using C# to build an application.

1) I have two windows forms, A and B.
2) A uses a DataSet read from SQL server.
3) The user presses a button on A to open B.
4) B is passed a pointer to the DataSet.
5) While in B, tables in the Dataset are bound to combo
box controls.
6) While in B, I add handlers to capture the
SelectedIndexChanged event
7) The user closes B
8) The user presses a button on A that causes the
DataSet to reload.
9) [THE PROBLEM!!!] - The event handlers that I set up
for B are still being called!


Questions:
A) Is there a way I can simply delete the form B object?
I tried calling B.Dispose() but it doesn't get rid of B

B) Is there a recommended method to deterministically
disable event handlers when a form is closed?

C) Why should this even occur? It just doesn't make sense
that the handler for a button that is on a closed form is
active when the form is closed?

Thanks,

Scott