Plugin not loading in IE7

My client uses IE7 and noticed this afternoon that the plugin is not loading. He was able to see the plugin earlier in the day and added a lot of events to the calendar during that period. I confirmed by switching to IE7 mode in dev tools on IE8.

I’ve done minimal work on the site during this time period. I essentially just updated CSS and added one image size to functions.php.

Plugin is fine on IE8 and Firefox.

Any help you can provide would be appreciated.