Hi Tracy,
Thanks for the post.
Login to PMP as admin and navigate to Resources tab. Look for this WindowsDomain resource and select the Verify password button next to this domain account. Check if the verify works fine. Then try to use the Change Password button and see if the reset works fine. If not, edit this resource and enable the "Supply Credentials" option. Choose a domain admin account and save it.
Then the reset will work manually and also when the user checks out the password using the Access Control feature. Please try the same and let us know how it goes.