Disappearing Data

Two Apple apps are misbehaving.

Mail - I'll choose an email - it'll be totally blank, in every regard. Even though it wasn't a few days ago.

Contacts/Address Book - enter information for a new contact - 'save' - it all disappears - the page on which I just entered the information will be blank - the listing will be 'No Name'.

Related?

More importantly - how to rectify?

I have tried contacts on a new user account - works fine - so what do I ditch from the problematic Library to rectify this?

Regards,

Edward