Problems with PDFs since upgrading to WordPress 4.4

Hi there,

I upgraded to 4.4 this morning, and thought everything was okay.

But I've just discovered that the PDFs within our website do not open when the site is being viewed in Chrome - all you get when you click on the links is a black screen and a graphic of a sad face :slight_frown: !!!

Everything operates as normal when the site is viewed in Internet Explorer... (I've not been able to check functionality in Firefox...)

Any thoughts?! Thanks for your help.