Error downloading codec

I have a couple of MPEG files that are not played properly by WMP10 (it
shows the "error downloading codec" message). I have configured WMP10 to
download codes automatically, and for most cases this works fine, but not
for all cases.

I have run GSpot on these problem MPEGs and GSpot renders them successfully
and does not report any problems. How can I know which codecs are missing
and how do I get/install them?



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