OK, I figured this out. Jim - a Windows issue, yes, now it is, but the change was made by Media Center and not restored on uninstall, leaving it to the user to figure out how to fix. I call that a problem with Media Center not completely uninstalling what it has done to the user's system. It is not harmfull to files, but is very alarming to anyone who has not modified this before.
I tried not to say file extension, but I see that I did. It is the file type, which has to do with default application to open the file. Using a command prompt window, I could see that the file extension was in fact intact - much relieved at that point.
To fix this, you do indeed go to Tools/Folder Options/File Types as you suggested in the first thread. Then, for each file extension, when selected from the list, it will now show blank in the "opens with" field in the details block below. Clicking change, and then select from a list since it has no suggestions, gets you the option to select Windows Media Player, which once selected will then allow all files of this type to have a type description representative of it's extension.
What still worries me, after the fact that the "opens with" field was blanked by Media Center, is that when the field is blank, my computer still defaults to a type of "MediaCenter.12.file" after "completely" uninstalling the software. I don't see any harm from it, however.
Thanks for the responses, and hopefully my more detailed follow up here can help the next person with this issue.
Hondo