Can’t open attachments in Outlook email messages – get pop-up question instead regarding bay178.afx.ms

When I try to open an attachment in an Outlook email message, I get the following pop-up:

Do you want to save GetAttachment_aspx?file=6ed80a17-d782-4fe2-8bcd-........from bay178.afx.ms?

At that point, I can't save or cancel the pop-up nor can I open the attachment. A search of the Internet seems to associate bay178.afx.ms with an organization called Hip-Hop International in the Bahamas. My guess is that my son downloaded something from that Web site while I was on vacation.

How do I get rid of that file / pop-up and allow myself to open attachments in Outlook again. I am using Windows 7 Home Premium on a Toshiba Satellite laptop.