Windows Movie Hit or Miss on Playback

My 458MB home movie (slide show with music) just streamed perfectly from my digital media library through my wireless router to the WDTVLIVEPLUS, using Digital Media Servers on the Player.  I first had tried Network shares, but the movie “bogged down” about 1 minute in; images were very slow, and the audio dropped out.

Yesterday, both Network Shares and Media Servers “bogged down” at about the halfway mark (7 minutes into 14 minute movie).  Today, I made sure all the RF sources in the house were off except the PC with the media library, the WDTVLIVEPLUS, the surround sound receiver, and the HDTV.  As I mentioned above, I got a good result with Media Servers, but Network Shares bogged down.

I can play purchased music videos in a 18 minute playlist without any problems, (regardless of how many other RF sources are active in the house) so I must be having bandwidth and/or signal strength issues with my .wmv movie.

Based on my description, can someone describe what is going on in terms of the physics? , i.e., is there a cache somewhere that gets depleted?  The router is an E3000; is there anything that could be done to increase its data rate, for instance…could I improve things with a repeater or booster (which is best?).  Thanks.