I wasn't being nosey, I was looking for a little more in depth info, such as what you've written it in!
Taking a bit of a stab in the dark here due to lack of info, are you by chance trying to open a file created in a recent version of microsoft word on a computer that has a early version of word installed? if so you have two choices, either save the file as a word 97/2000 format on the original computer, or install the docx converter on the second computer.
http://www.microsoft....cd1466&displaylang=en
However, as I said I'm taking a educated guess due to lack of relevant info.