Computer and chili tech camera problem.

[slappy]

I have one of those cheap chili tech cameras on my fazer that has worked ok for about a year and now I am having a strange problem with. If I import the videos to my laptop some of the videos play perfectly using windows media player but some videos will not play at all and I get the message that the format is not recognised. I have tried using the HP videosmart program supplied with my laptop but I just get the same message.
Anyone know how to get round this? ( bearing in mind my computer skills are getting pushed to the limit just importing videos).