Camera help! i cant figure this out!!?

my friend has the same camera as me, " casio Exlim 8.1 mega pixels" ok so i make a video on the camera and put it on my computer and when i try to open it from windows moviemaker to edit it...it says " error the file CIMG182 can not be opend" something like that ..... i dont know what it means and then i cant edit my video :( BUT my friend can and we have the same camera i made all of my settings EXACTLY like herws but it still wont work