I must have got an MP3 file in my temp folder; that is my best guess how it happened. I wanted to sort the files by date and found that the folder was being treated as a media folder. None of these files have "Artists", "Album" or "Genre" meta data! I right-clicked on the columns to modify what columns exist, but again all were related to media files (no date created).

Right click in the white-space (not on a column or file) and choose "Customize This Folder…" (or choose properties for the folder and navigate to the "Customize" tab).

At the top you'll see "What kind of folder do you want?" along with the option "Use this folder type as a template". In my case "Music Details" was mistakenly the option selected. There are also choices for "All Items", "Documents", "Pictures and Videos", and "Music Icons". These options represent selections of not only sets of columns you can view by default but it also affects the toolbar at the top: if you choose "Pictures and Videos" you'll see "Slide Show" appear as an option. if you choose "Music Icons" you'll see "Burn" (actually you get "Burn" for a lot of the options).

In my case, choosing "Documents" or "All Items" got me back to a "normal" folder where I could again sort the files by date as I had wanted.