According to Adobe, if you are having trouble loading the invitation then make this simple change to the Adobe Acrobat Reader settings.
Step 1: Open Acrobat Reader
Step 2: Click Edit, Preferences, Internet Settings
Step 3: Remove the check mark from "Allow Fast Web View" in the Web Browser Options
Step 4: Close Acrobat Reader
You should now be able to open the invitation.
If the margins are not correct, check the scaling setting in the print menu. Select "none".