Some progress. If I move the option group box off of those labels, all but the three checkboxes stay normal during switching.
I think it would be be a good idea to answer George's question! What version/service pack of Access are you using? Also, what OS?
I'm running v2003/SP2 with "Use Windows Themes" checked, running under Windows XP using Windows Classic Style, and like George, it doesn't happen for me.
What are you running, Bob, when the aberration does occur?