#27 video prewiew doesn't work

[virginia sacchi]

i just downloaded vss the latest version, my operating system is vista; the problem is about the video that might be showing on the right side; the video remains black, audio is workingh though, and the video appears in some flash if i drag the window for the video around the page, but it appears for one second (correctly displyed with audio) and then just desappears. i try it with different files and always the same. i downloaded the codec too, obviously. audio is working fine.