[Koha] name-based virtualhost problem

I would appreciate some help diagnosing a problem. I have three package installed Koha instances running on a Debian server, for a number of weeks all has been OK but today the opac address for one instance leads to the opac of another. The admin interface operates without issue though. I have reloaded the config and restarted apache but the problem remains. Any assistance would be appreciated. Clint. -- Clint Deckard Ashley Clinton RD1 Takapau Central Hawkes Bay, New Zealand.