ActiveMovie is a part of the DirectShow component of DirectX. DirectShow is used to provide MP3 sound streaming.
So you have a bad codec for MP3 play - as already covered in this sticky thread above.
link
solutions:
switch all sounds off as described in that thread and play without sound.
or:
As you installed the third-party application with the problem codecs, then you will have to figure out how to repair these or return to the Microsoft default ones.
or:
Convert to the WAV sound file format. As described in the thread, there are instructions how to use goldwave in \game data\sounds\WAV\SOUND_PROBLEMS.txt
or:
Wait for the 3.5 patch which should be with you in a week or 2. Since so many third-party codecs have problems with directplay, we have given up on the compressed MP3 sound file format and will be using WAV. Version 3.5 (I think) has the larger WAV format sound files included.
Cheers
Andy