file attachments

It sounds like you may not have the required programs on your computer to open those documents.  PDF requires at least Adobe Acrobat Reader which is free at http://www.adobe.com.  The .docx files require Microsoft Office 2007 to open.  If you have an older version of Microsoft Office there is a compatibility update you can get from http://www.microsoft.com/en-us/download/details.aspx?id=3.

Also, what is the error you get when you try? Could be your Program defaults, but I will only go into that if Chris' answer didn't answer your question.