PDF documents prompting "Checkout & Open", "Open", or "Cancel" even when user has only "View Only" rights

My users who have "View Only" permissions are getting prompted to "Checkout & Open", "Open", or "Cancel" when they click on a pdf document.  I have require check out turned off. I even turned off versioning.  I don't understand why they are getting this prompt when they don't even have permissions to edit anything.

I would like it so that it opens directly in Adobe Reader without a prompt at all.  (at the very least, no "checkout & open" option).

Does anyone know a way to do this? Do I need to unistall Adobe PDF iFilter?

By the way, we are running IE9 but I had a user try it on IE8 with the same results.  It works perfectly in Firefox with NO prompts.

Thanks for any help.