Video File Seeking in WMP Vista

I'm having some problems seeking to different sections of video files with
the progress slider.

For certain file types (such as AVI or Flash) I AM NOT able to use the
slider to seek to different parts of the video when i open it from the Media
Player Library. The slider does not move from the far left, and if i try to
move it the file restarts from the beginning.

However, when i open the same files by clicking them from their folder in
explorer I AM able to seek with the slider through any parts of the video.

I have tried installing different codecs and it didnt solve the problem.
Anyone else experience this or know how to fix it?

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