Here's the situation.
Someone was using shared contacts, editing and updating and other stuff. I had to turn off caching on that machine due to some calendar sync issues. After that the said shared contacts stopped working. It appears the user box (owner of the shared contacts) had been terminated long ago and all the "shared" contacts were actually stored in local cache.
Is there a way to import the Contacts from cache? It's a question of 600 contacts lost...
