Not sure why you are experiencing this however the module feature works on my test site as normal. This leads me to believe either the file is corrupted or you be experiencing an intermittent issue with the .png file.
If still having troubles try test on another browser. If no luck provide the url of this page so we can investigate further.
Looks like this is actually a bug for newly created sites.
"What happens is for sites created after the last release (when the Report abuse link was introduced) the literature items are corrupted when being downloaded and cannot be opened. "
We are aware of the issue and will fix this in an upcoming release. This appears for certain type of files such as png and jpg. When testing with a txt file it works fine within your site.
Thanks for the heads up and for your patience as we look to correct this soon.
Europe, Middle East and Africa