Adobe Acrobat Pro only opens certain pdf through internet explorer

Greetings!

I am an employee at Shaw AFB, and we have ran into an issue after Adobe Acrobat Pro XI was updated on our systems.

I can open a test pdf from a website, and it will open within the browser.

When I access another site, like a school website, to access a newsletter, which is in pdf format, it shows a black X near the top left of the page.

I am unsure what is causing this to happen, or if something is blocking it.

Very confused.  Has anyone else seen this issue?

V/r

Juan