Most likely it is an issue with timing. When you run an action that runs an action group, that group runs independently of the actions that follow the launching action. This is kind of hard to explain. Suppose you have 5 actions on a button and action 2 runs an action group. Now you might think that all the actions in the action group would complete BEFORE action 3 runs. Not so. As soon as the action group specified in action 2 starts, the browser will run action 3. If action 3 also runs an action group, its actions may be interspersed with those in the action group run by action 2.
For example, if action 2 runs a group that has actions that hide a bunch of text boxes, and action 3 shows one of those text boxes, action 3 may run before the action in the action group that hides the same box is run. As a result, the text box in action 3 may end up hidden instead of showing like you would think.
