The internal MPEG-4 appears to be incompatible with a number of MPEG-4 videos at various customer installations. To disable this codec, open the following file using notepad:
c:\users\public\documents\dcmedia\dcmediaplayer.ini
Add the following section at the end of the file:
[dshow]
useinternal=0
Save the file. If you don't have any other MPEG-4 codec installed, download and install the CCCP codec pack.