You may not be able to open an attachment because you either don't have the right software program to open the file, or the version of the software you have is too old. Check with your instructor to find out what software and version was used to create the document.
Some of the Blackboard pages may have content that requires a plug-in or other software to be viewed. Plug-ins are small software programs that let you hear music or other sounds, watch full-motion video, or enjoy multimedia presentations. Here is list of recommended plug-ins.
Also, if you do not have Microsoft Office (Microsoft Word, Excel, or PowerPoint) these free downloads will allow you to view files created using Word (.doc), Excel (.xls), or PowerPoint (.ppt).