Microsoft Outlook uses an add-in to work with Adobe Acrobat. Perhaps in either Office or Adobe Reader (the free version of Acrobat), you somehow have picked up the installer for Acrobat Standard or Professional. Adobe Reader lets you open and print PDFs, as do the paid versions of Acrobat. If, for some reason, the installations mingle, things gett messed up. It happens.
It's a rude cure, but the most thorough thing to do would be to:
1) Uninstall Acrobat on your system.
2) Use Adobe's AcroCleaner tool to remove any remaining remnants of your Acrobat install(s).
3) Reinstall Adobe Reader on your system. First make sure before you download the program that you scroll down and uncheck the More Add-Ons section to not install McAfee Security Scan Plus if you don't want the additional download on your system.
Or, you can continue to download your PDFs, open them in Adobe Reader and print them from there as you're doing right now. Either course of action should work for you.
Hope this helps,
Randy