Thanks Dwayne and Ben. I've run the page in debug mode and there aren't any problems occurring. The problem only appears in Internet Explorer 6. When run in Internet Explorer 7, there aren't any issues with things hiding when they're supposed to or things showing up when they're supposed to.
As for the timing, the ONLY action triggered by the button is to run the action group. The action groups themselves tend to have many actions in them. For example, Button One's action is to run Action Group One (hide img_one, hide txt_content_1, hide txt_directions_1, hide btn_one, show img_two, show txt_content_2, show txt_directions_2, show btn_two). Button Two's action would then to be run Action Group Two, which would have a list of actions similar to what Action Group One has.
Any ideas why this would act funky in ONLY Internet Explorer 6 and not IE7? Does anyone know of problems or limitations associated with the NUMBER of actions that can be triggered in one action group?