Membership 2.0: unable to login as member

Hello,
members are no longer able to login using their credentials. I have checked their credentials and they are correctly subscribed with billed payment. Same problem with my test membership account. The plugin has just been updated to the latest version 1.0.3.3
Login/registration page:
http://www.craniosacrale.it/community/area-abbonati/

Thanks in advance,
Francesco