single class instance question

Hi All,
  Other than through tight source code control, Is there anyway to keep
multiple instances of a specific class from being created in the same
program? For example, say I have a class MyClass and somewhere else in the
code I have an instance of MyClass called MyInstance. Is there anyway to
keep additional instances of MyClass from being created once MyInstance has
been created? This is only a potential problem because multiple programmers
will be working on this particular project.

  I can hear the question now, "Why are multiple instances of the class a
problem?" The reason is because the class contains functionality that I
don't want conflicting with another instance of itself. Any ideas on how to
prevent this?

  I managed to increment an 'instance' counter that increments by 1 each
time the class constructor is called and inside the constructor I check to
see if the counter == 1 or not and if not, then I branch to an 'else' block
and call the class destructor on the second (or subsequent) instance. The
problem is that I can still call functions in the class through the second
instance, even after the destructor has been called on it.