I have received a number of e-mails that I cannot open because my system does not acknowledge it. All the e-mails have a joke that was sent to me. The problem is that they all end with a .pps which I cannot open. Can you advise. Thanks for your time.

You need to have Microsoft PowerPoint installed to view them.
You can try installing the free PP viewer from here:
http://www.microsoft.com/downloads/d...displaylang=en