try uninstalling the WinZip software then save the image as test and then go to the file and right click the file, and click rename and then edit the-ren-name of the image to test.png or test.bmp and when asked click yes to change the format, and let me know if that helps, changing the format of the file rename should allow you to change the extension of the file to open it to the format that you would like,
i hope this helps,
francis.