Incorrect time on Video clips

Sometimes when I play a video clip, the total time length is incorrect. For instance, a 10 minute clip may show up as only 3 minutes long, even though the whole clip is there. I can start in the middle and it will begin at the halfway point, but only continue for half of the 3 minutes. Does this in all media players; I am using Windows XP Pro. Any ideas as to how to make the time longer so I can view the full clip?