Branching

I have a situation that has become very frustrating and I'm not sure how to resolve the problem. Here's what's happening with my program. I have a form that has a command button and a combo listbox. When my program executes the code that is contained in the command button click event, it branches off and excutes the code that is contained in the dropdown event of the combo listbox. It then returns to the next statement in the command buttons and excutes the rest of the program. When I step through the code, I see where it branches off to the combo listbox. It branches off at the "combo1.topindex = 0" statement. Is there a way that I can prevent my program from branching and executing the code contained in the combo list box?

Thanks,
Darryl