[IainSkelly]

I have a laptop running Vista Ultimate and a Desktop running Vista 64 Home Premium. I have several networked devices accessing the Media Player's library (on both machines) using UPNP. Both Media Players can play Divx, MP4 videos etc (using ffdshow codecs)on the computer. However my networked devices can only access Divx and MP4 from the laptop (running Vista Ultimate), they cannot play video (other than WMV) from the Home Premium Vista. One device can see the files, but gets an "invalid file type" error when I attempt to play it (even though if I copy that file to the Vista ultimate all devices can see it and play it normally). Even when I use my Laptop to access the media Library on my desktop, MP4 and Divx files do not show up (though the desktop lists all these files in its library and plays them all perfectly). File associations appear to be irrelevant. I can access the files in other ways (SAMBA) fine from both machines, but my Philips TV only supports UPNP.
I have come to the conclusion that there is a difference between Ultimate and Home Premium in relation to the Media Player Library and UPNP - has anybody had a similar problem?