WMP9 plays MPEG1 audio but not video ??

Hi,

I have a MPEG1 file (xxx.mpg) where I can hear audio but not see video. I get no error message when I start playing back this file.
If I use GSPOT, it tells me theat both AUDIO & VIDEO codecs for this file are installed but I still cannot see any video.
Even more surprising is that WMP9 tells me that the file is 384x288 (file properties) whereas GSPOT says 352x288 !!!!

I also have Directx 9.0c installed with everything ok.

Any idea what to do to solve this issue ?