Horrible fatal errors (Polylang?)

[silvenon]

I connected your plugin to my MailChimp account, everything seemed to be working fine, except it wasn't playing well with the Polylang plugin, so I couldn't translate it. Then, a week or two later my site collapsed! Well, not actually collapsed, but there were about 4 error warnings on the top of the site and in the admin interface! Special characters were displaying awkwardly and there were tons of errors displaying on pretty much everything I did, except when I disabled the plugin, which made the errors go away.

Anyways, here are the errors:

Warning: spl_autoload() [function.spl-autoload]: Unable to access wp_widget_calendar.class.php in /home/synergyc/public_html/wp-content/plugins/mailchimp-widget/mailchimp-widget.php on line 37
Warning: spl_autoload() [function.spl-autoload]: Unable to access ahm_plugin.class.php in /home/synergyc/public_html/wp-content/plugins/mailchimp-widget/mailchimp-widget.php on line 37
Warning: Cannot modify header information - headers already sent by (output started at /home/synergyc/public_html/wp-content/plugins/mailchimp-widget/mailchimp-widget.php:37) in /home/synergyc/public_html/wp-content/plugins/polylang/include/core.php on line 199

The last one is about Polylang, so maybe the combination of the two causes the problem.