Correct comments: this is a .png file, thus windows will try to open it in the default image viewer. It is true that some image files can contain a payload... .png don't have much room for a payload in the compression.
incorrect: image payloads are not the reason why many email programs don't automatically load them. the issue there is images in emails in html mode can be loaded from the web, thus alerting the sender of the email that someone viewed their email, cause the image was downloaded. Thus they then would know your ip address.
the message going around says that Avast detects it... Avast has NOTHING on their website about it.
But, basic internet security here.
Don't open attachments from anyone in skype unless they're sending you a file you're expecting, and you scan it before opening it.