Mail (6.3) not working with Contacts (7.1)

Couple of weeks ago, Mail had a nervous breakdown. Deleting data per suggestion Mail was restored. However, I come to notice that saving a new email address puts it into a contacts list controlled by Mail which doesn't allow for any editing. Trying to send an email from the Contact app does not allow an option to send an email. Trying to send an email to a group does work to the point of opening a new email, but unfortunately only with the name of the group in the address line - which is immediately flagged as an error.

Is the breakage on the mail side (seems likely) or on the contacts side?

Side point - previously mail accessed Yahoo mail as a POP account; recovering mail service now uses IMAP to access Yahoo (seemingly a change for the worse, response time etc.)

Really would like my dependable Mail and Address Book back!!!

Thanks for any suggestions.