Go to Edit>Preferences>Documents>PDF/A View mode and switch it to "never".
This only helps if the form is saved to the desktop or a network drive. We need to fix the problem in IE. Rebooting didn't help. Disabling and reenabling the add-in didn't help. Would try to reregister the Active-X control but can't find AcroIEFavclient.dll in the source files.