Ads don′t work after 3.4.2 update

After the update to 3.4.2, all my ads are gone on my WordPress multisite network. I use OpenX, and when I log in to my account with OpenX is the following message:

Dashboard Error

XML-RPC connection error (code: 800)

System message: XML-RPC connection error

The dashboard pulls information from a central server for some widgets. There are Several things Which can Affect this.
Your server may not have the the curl extension enabled. You may need to install or enable the curl extension, see here for more details.
You should check overpriced That isn’ta your firewall blocking outbound connections.

Can someone please tell what might be wrong?

Thank you! =)