Whenever I open Mach3, I end up with an error message that states " Initialization Macro called upon reset". What is it and how do I rectify the problem?

That is not an 'error', it is just informational. If you look in the general configuration window, you will see a section that controls what happens on initialization/start up (called Startup Modals). Generally it is a very good idea to have your control start up in a known state so if you try and jog you know what will happen (for example). The message is just letting you know that the initialization has been done.

Thank you very much for your quick response.