Problem playing clip referenced with ASX metadata

This is a strange one. I have a laptop with Windows Media Player 10
installed. Using IE 6, I access a local web page which has an embedded
Active-X Media Player control in it. The player loads the URL which resolves
to some ASX meta data. For example:

<object id="mediaplayer"
width="500"
height="500"
CLASSID="CLSID:6BF52A52-394A-11d3-B153-00C04F79FAA6"
type="application/x-oleobject">
<param name="URL" value="http://localhost/generateASX"/>
<!-- BEGIN GECKO EMBED... although as noted above...scripting won't work -->
<embed type="application/x-mplayer2"

pluginspage="http://www.microsoft.com/isapi/redir.dll?prd=windows&sbp=mediaplayer&ar=Media&sba =Plugin&"
src="http://localhost/generateASX"
name="MediaxPlayer1"
width="500"
height="500"
autosize="1"
animationatstart="0"
stretchtofit="true"
autoStart="false" />
<!-- END gecko code -->
</object>


The URL points to some ASX whose which has a <REF HREF .... > which points
to a local file, eg. <REF HREF="file://C:/video.wmv"/>

The ASX file also contains a STARTTIME and DURATION (which effectively clips
the playback time to a portion of video.wmv).

When I disconnect the laptop from the network and open this ASX file from
the Active-X control it does not play the video. All I get is a blank black
screen.

If I change the ASX and remove the STARTIME and keep the DURATION it will
play fine.

If I open the ASX file directly by double clicking on it, it will play the
clip (in a Windows Media Player application instance), begining at the offset
specified by the STARTTIME just fine.

If I connect to the network such that I have BOTH and IP Address AND my
network interface card has established a link, the Acive-X control will play
the clip.

If I then disconnect from the network and remove the IP address, thus
returning to the original configuraiton I can load the ASX file via the
Active-X control and it will play.

This seems like I have uncovered a bug here or is this inconsistent behavior
documented somewhere?

TIA

DW