I've tried on Windows 7 64-bit and Windows 10 64-bit. I get this LocalService.dll error whenever I try to launch the portable version.
If I have FoxIt Reader (portable) already running, the PDF open fine.
I've tried to open attachments from Windows 10 Mail and Windows 7 Outlook 2013 FYI.
Perhaps with the 9.4 security update, this can be looked at too?