The login (wp-login.php), registration (wp-login.php?action=register) and forgotten password (wp-login.php?action=lostpassword) urls work fine.
However, if I trigger the recover password function, the url in the subsequent email has wp-login.php?action=rp&key=ZZZZZZ&login=yyyy in the confirmation url. This url generates a 404 - not found.
I can confirm that de-activating the plugin allows normal functionality.
Any ideas how I can fix this? Thanks.