Javascript error in IE8

When I log into Crucible with IE 8, I get the following JavaScript error on every page:

'type' is null or not an object concat.aui.c8771d475e8b0ad1d340db23860de48d.cache.js, line 35 character 26131

The error doesn’t fire when the page loads, it fires when I click on a link or do something that tries to navigate away from the current page.