Resolving a wall less than 150mm error message?

Whenever a modelled internal or external zone walls are 150mm, 100mm or 50mm apart the following error message will pop up.  Simply find the zone which has intersecting walls which have been modelled 150mm or less apart and re-zone to ensure the walls are at least 150mm apart from each other.

                                                                                                          Zones modelled less than 150mm apart