I had posted this question before but no one seemed to pinpoint what was wrong. I'll just explain that I have windows 7 and with it (I believe) came with DVD maker. I've used it before and had no problems but now, any time I choose the burn to DVD option on windows movie maker, it opens DVD maker but always prompts me with this:

"0 files were successfully added. 1 file could not be added. The file C:UserUsernameDesktopMy movie.wmv is not a supported file type, and it cannot be imported."

If needed, here's the old discussion: http://answers.microsoft.com/en-us/windowslive/forum/moviemaker-files/cant-save-a-burn-to-dvd-file-to-msdvd-or/5d31ddfe-9ac6-471d-ae02-dd90abb6eeb8?tm=1429330876455