I honestly think it's actually a .png file.
Reasoning:
A) It could be perfectly resized.
B) The dimensions of the file's icon seem to be correct. Windows 7 draws previews of a picture on a desktop.
C) You can hide extensions of known filetypes, in this case, a .png file. It's real name would be "new 3.txt.png".
D) A .png of that dimensions could be 3.26 MB.
Still, it may just be some odd glitch.
Then again, I'm starting to think it's edited.
The attributes being shown aren't lined up right.