Can't install any plugins since update

We've not being able to connect to the dashboard because of this error.

Your server had a problem connecting to WPMU DEV: "HTTP Error: 403 "Forbidden"". Please try again.If this problem continues, please contact your host with this error message and ask:"Is php on my server properly configured to be able to contact with a POST HTTP request via fsockopen or CURL?"

We have contact our hosting which is Media Temple and everything looks fine and our server DV does allow CURL! And we had another site on the same server/DV ( working fine but after update the Dashboard the same problem again.