Windows Live Mail (and other mail) – Opening Attachments

Ever since switching to Live Mail, my wife has been unable to open any attachment, such as a Word or Excel document, unless the program is already running. If the program is already running, then the “open” seems to send the machine into a frenzy of reading often ending in an “Not Responding” message. She can save the attachment first but this is obviously much more time-consuming. In “ordinary” Hotmail or Outlook Express, “open” at least does cause the relevant program to kick off automatically but again there is now a great deal of often disk activity that often ends up with equal lack of response. Can any knowledgeable reader out there please explain all of this to me – and even possibly offer a remedy ?