File Sort Anomoly

When I open My Documents and click the column to "sort by file type" I get my "*.png" image files nested within my Word document files. Why would that happen?

Yes they are in My Documents.

I assumed that when I sorted by file type it would separate out the .png's into a separate Icon category and I did not expect to see .png file Icons nested among the Word Document Icons.

After reading your response, I noted the following:
First come the Word Documents Icons with docx extensions.
Second come the Picture Files with .png extensions.
Third it switches back to Word Icons, but this time with .rtf extensions.
So it seems they are being sorted by file type extensions. But because the Word Icon is used for both Word .docx files and .rtf files, the .png files sneak in there among the Word Icons since the sort is done by extension rather than by Icon (which Icon may be used for more than one extension type). I just never noticed this before, or as you pointed out, maybe this is because I previously saved them to My Pictures whereas this time they went to My Documents.

So the issue is solved, they are being properly sorted by extension. The confusion on my part came in because several extensions can share the same Icon. I was expecting the sort to show by Icon but it is by extension (regardless of Icon since extensions can share Icons).