A common issue seen by windows users after downloading a report, is that, they are unable to open the downloaded report file.
If the error is like the one above, go to the folder in which the file is saved. Right click on the file and click rename. Give a short name and then try opening it.
If your issue is specifically related to a survey report, have a read of this article - Why can't I unzip my survey report.
If your issue still persists give us a shout.