Portable document format (PDF) files remain a popular choice for business documents ranging from contracts and forms to manuals and reports, so there's a good chance you need to open them often.

Q: Sometimes when I try to open a file or e-mail I get the message: "The selected file has an extension (PDF) that is not recognized by Windows Media Player but the player may be able to play it.

PDFs have become quite a staple in our digital lives, and it's likely that you use them more often than you realize. Perhaps you're a student doing research for multiple school projects, or possibly ...