On all my Admin screens, I have a permanent "Connection Error! Please try again..." message, just below the About WordPress icon
I also get the message when uploading new media files using the multi upload files option (even though the files do get uploaded), and I can't delete plugin files that I don't want. Otherwise I can post, update pages no problem.
This installation is running on CentOS 6.5 with PHP 5.3 and Apache/2.2.15. I am using the latest Creativo Theme.
As the site is within my company firewall, I can't give anyone access.