Log in Problem

Greeting,
I Don't know if this is the correct forum, but since a couple of days I'm experiencing the following issue:

When I try to login, all seems fine, I receive the related points, but I cannot donwload anyfile because instead of the relative link I find the statement "To see the download link become a member", even if I'm already loggedin.

How can I fix this problem?

Thanks and best regards