MailChimp plugin error

I just noticed that the latest mailchimp plugin is causing an error on my site. The plugin was working fine days ago. I resaved options. Redownloaded and installed plugin. I get the following, no matter what:

On the front end sidebar:
There was a problem loading your MailChimp details. Please re-run the setup process under Settings->MailChimp Setup

In settings > mailchimp:
Warning: Invalid argument supplied for foreach() in /home/mysite/public_html/wp-content/plugins/mailchimp/mailchimp.php on line 586