This may be because your file is a NSV 264 Codec.
First of all, download the 'ffdshow' and the x264 installer here.
Then, you will need the plug in for Winamp, which can be found here.
Right, so you install the ffdshow installer and just keep pressing next... after its done you extract the files of the nsv_x264.rar into your winamp\plugins folder.
Ok, so now go to start/programs/ffdshow/vfw codec configuration.
1) First, click on the 'decoder' tab.
2) Click on the 'codec' menu.
3) Right mouseclick on 'H.264'.
4) Click on 'Set all stable formats to libavcodec'
5) Click on 'apply'.
6) Then 'ok'.
Hopefully, that should fix up your problem.
It didn’t work for me. All that happened is that the DVD opneed in Media Player and showed only the warning at the beginning and then the first title picture . Nothing else! It wouldn’t play any more of it. In fact the program crashed! I couldn’t even close down Media Player. I had to force it to close with the Task Manager! Incidentally, I do have the K-Lite codec pack installed too!