I am using the K9 email app on my 4G Touch. I receive an email with a .doc, .xls, or .ppt attached file, and when I tap on "open" I get a pop-up message the document can't be opened. I open the Polaris app and it wants me to register. If I tap later, then the My Files directory opens. I am not fond of the stock email app. Those of you using K9, are you able to open the above mentioned attachments?