I'm new to forum and not very knowledgeable when it comes to my computer, so I need answers in very simple terms. I have a E-machine, Windows XP Home Edition, 2006, with HP media center and it appears that I lost or accidently deleted the "Document Viewer" program. Error message is that program can not be found. How do I reinstall this program? Do I need to backup or save any data before I re-install? Thank you for any help.