Typical issues when you start Hearthbuddy can be fixed this way :
1. Check heartbuddy has access to the net (for auth & updates) => check firewalls...
2. Be sure you have the lastest update avaible (maybe auto updater wont work)
3. Start Hearhstone as normal user (not admin) and start Hearthbuddy as admin
3. If it still wont work, send a post on hearthbuddy forum with your log as attachement.