login problems after moving database

My hosting company has successfully transferred database of my wp blog http://djavadi.net to another server on wp to create a new url. Transfer was fine, all files etc. in new place http://cheshmandaz.org. I have also changed domain and site address on admin/settings/general from the first to the new site. I also have forwarded the old domain to the new one. BUT now, it seems the new url and admin page don’t recognize me: I have constant problems with my log-in: set passwords are accepted once and then rejected so that I have to go for “Forgot the password” and renew the password. Also, when I log in, the admin bar doesn’t show up when viewing the front end of the site. Also: when viewing the site, it doesn’t show me as logged in. How can I fix this? Any help is much appreciated.