Excel VBA Error Message
 

I have an excel vba routine that uses a user form to
control processing of a "catalog" of information on a
worksheet. The code executes perfectly the 1st time it is
called after the application has been opened. If I execute
it a 2nd time I frequently get either an excel crash or an
excel error message that says "The object invoked has
disconnected from its client" . This message is followed
by an excel crash. I have no idea what this means. Help is
appreciated.

The code is invoked by clicking a control button.