Empty cart por anonymus users

Hi:
Today i've change my server provider and i have some problems, i think that is with the permissions

when i logged like admin i can add products to the cart without problems, but when i'm not loged, like an anonymus user, i see the notice that i've add the product to the cart, but when i go to the cart it's said that the cart it's empty.
It's very strage.

Also i can't log in like a normal user

Anybody know what it is?
Thank you.