ppt attachments

I have been using this wonderful system (MHonArc 2.2.0) for a couple of
months now.  Can't say enough good things about it.

I have just recently run into a snag.  I can open/save all attachments
except the MS powerpoint. MS Powerpoint can't open the file. File types
of XLS, ZIP, DOC all seem to work just fine. It is only "ppt" files I am
having difficulty with.

Has anyone else had this kind of problem? What can I do about it?

-= joe =-