MP4 playback issues

hi guys, i’m from the UK and own a 1080P Media Player:

http://www.amazon.co.uk/Western-Digital-1080P-Media-Player/dp/B002VAVR4A/ref=sr_1_4?ie=UTF8&qid=1290…

Firmware version: 1.01.70

i connect it to a WD 2TB MyBook Studio Edition II for viewing movies on an HD TV.

Seems MKV or AVI files work fine, no matter how large.

But on MP4 files the sound cuts out intermittently and also the video stutters.

playing back the same files from a wd passport through a PS3 - video and sound is perfect.

do i need to upgrade my hardware or software ???

Format                           : MPEG-4
Format profile                   : Base Media / Version 2
Codec ID                         : mp42
File size                        : 1.25 GiB
Duration                         : 1h 46mn
Overall bit rate                 : 1 685 Kbps
Encoded date                     : UTC 2010-07-22 13:02:51
Tagged date                      : UTC 2010-07-22 13:02:51

Video
ID                               : 1
Format                           : AVC
Format/Info                      : Advanced Video Codec
Format profile                   : High@L4.1
Format settings, CABAC           : Yes
Format settings, ReFrames        : 3 frames
Codec ID                         : avc1
Codec ID/Info                    : Advanced Video Coding
Duration                         : 1h 46mn
Bit rate mode                    : Variable
Bit rate                         : 1 256 Kbps
Maximum bit rate                 : 5 213 Kbps
Width                            : 720 pixels
Height                           : 384 pixels
Display aspect ratio             : 1.875
Frame rate mode                  : Constant
Frame rate                       : 23.976 fps
Color space                      : YUV
Chroma subsampling               : 4:2:0
Bit depth                        : 8 bits
Scan type                        : Progressive
Bits/(Pixel*Frame)               : 0.189
Stream size                      : 958 MiB (75%)
Writing library                  : x264 core 67 r1162M f7bfcfa
Encoding settings                : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=umh / subme=7 / psy_rd=1.0:0.0 / mixed_ref=1 / me_range=12 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / chroma_qp_offset=-2 / threads=12 / nr=0 / decimate=1 / mbaff=0 / bframes=3 / b_pyramid=0 / b_adapt=2 / b_bias=0 / direct=3 / wpredb=1 / keyint=250 / keyint_min=25 / scenecut=40 / rc=2pass / bitrate=1256 / ratetol=1.0 / qcomp=0.50 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=24000 / vbv_bufsize=24000 / ip_ratio=1.10 / pb_ratio=1.10 / aq=1:1.00
Encoded date                     : UTC 2010-07-22 13:02:51
Tagged date                      : UTC 2010-07-22 13:04:27

Audio #1
ID                               : 2
Format                           : AAC
Format/Info                      : Advanced Audio Codec
Format version                   : Version 4
Format profile                   : LC
Format settings, SBR             : No
Codec ID                         : 40
Duration                         : 1h 46mn
Bit rate mode                    : Variable
Bit rate                         : 125 Kbps
Maximum bit rate                 : 148 Kbps
Channel(s)                       : 2 channels
Channel positions                : Front: L R
Sampling rate                    : 48.0 KHz
Stream size                      : 95.3 MiB (7%)
Encoded date                     : UTC 2010-07-22 13:03:06
Tagged date                      : UTC 2010-07-22 13:04:27