This is not a virus. I promise. [Solution posted]

But it's always good to be on guard... :-)

http://yirg.sent.com/Puzzle

Solution: The file is indeed not a virus, but a simple image of the GA code. I saved it as an XCF file using GIMP image editor, and then removed the file extension to make things a bit less obvious and a bit more suspicious. To identify the file format, just open the file in Notepad and you'll see the text "gimp xcf file" in the beginning. At this point you just need to install GIMP and open the file from there.

View attached image.