Try downloading VLC or Splash Lite and see if it plays fine in these media players or not. WMP isn't really accurate for viewing most video files IMO.
I pulled over VLC and it played without the these issues. It took it a split second to adjust when I would click ahead on the time bar a couple of minutes ahead, but no big deal.
My concern here wasn't so much being able to play the high bit rate version as it was concerns that I have some sort of software conflict, bad codecs, or what not. Would you expect WMP on a machine with this level of hardware capability to struggle a bit with the file described above?
WMP overall is a pretty unreliable media player IMO. The media players I tend to stick with are VLC,Splash Lite and KMplayer. In my experince sometimes with interlaced footage VLC doesn't play it back very well if it's a scene that has a lot of movement regardless of how you tweak it's deinterlace filters/options etc. So in those cases I use one of my other media players.
Basically what I'm saying is that no media player is perfect for every scenario although WMP is certainly my least favorite.