Hi Mary,
I have downloaded and installed ffdshow rev3355_20100411 following advise from the following website http://windows7news.com/2009/07/22/ultimate-guide-to-codecs-for-windows-7-media-center/
This appears to have resovled the issue - I do not appear to be getting the server execution errors anymore. However, I have all but given up on using Windows Media Player as a media player tool now as a result of this inconsistent error I was getting. I now have also installed Apple iTunes and DivX applications to play audio and movies.
I will now only use WMP's "Play To" feature to enable me to stream audio to my Samsung Home Theatre system, until another vendor provides a workable DLNA server that is easy to use.
Whilst the "attempts" you have made here may have assisted in working out a way around the problem, I don't believe that the Microsoft application that is supposed to be able to play media files is worthy of its effort - you should try the iTunes Genius feature - it is brillant. It is only that I have an interest in PC applications that I have persisted for so long in the various "suggestions made". Had I been someone with little to now knowledge of PC's other than the applications that it comes with, the directions and instructions provided by "Microsoft Answers" would have been lost long ago.
It is rather disappointing that the so-called Windows 7 replacement for the buggy Windows Vista is introducing basic file errors where no such file errors existed previously. With the all the faults that Vista had, WMP under Windows 7 appears less stable.
As for the Anti-Virus version, here it is... Avast Free Antivirus 5.0.507
I removed Picture Motion Browser Software long ago as it was a poor replacement to both Google's Picasa and (surprisingly Windows Live Photo Gallery) - as such I have not tried that application.
I'm rather surprised by your last comment about "Third Party Software" - what else is a person to use. I'm basically reading that as "if you have third party softwar, Microsoft will most likely blame that software first before looking into it's own backyard first". Having an MPEG2 / DVD Codec I would think is a basic expectation of any user from the worlds largest software manufacturer.
I wish all other readers of this thread the best of luck if they come across a similar issue that I (and others have had).
Gemdarwen.