Using DNN 7.2.2

The tabs on Site Settings do not collapse, they are presented as one page.

Click the black arrow to collapse I get this error in IE 11:

Forbidden

You do not have permission to access this document.

In Firefox no error is presented, the page does nothing.

If I click a tab (Basic Settings, Advanced Settings, User Account Settings, Style Sheet Editor), the page refreshes to the proper section of the page.

No errors are recorded in the Event Viewer

Tabs in page settings, module settings and host settings work okay, the problem is only on the Site Settings page.

There are no other modules on the Site Settings page and the error occurs regardless of the skin.

What else could this be?

Thanks.

Hi Ken,

Thanks for responding. 

We have a third party skin, however when I switch from that skin to one of the default DNN skins the problem remains.

I've cleared the application's cache and recycled the app pool with no result.

Also cleared cache of Fire Fox browser and IE browser.

I still get the error in IE.

There is no error in Fire Fox... but the collapse/expand doesn't work... there is no error reported. 

This is a site that was upgraded from DNN 6.2... and prior to that I believe 5.6.8.