I'm having issues previewing some pre-made templates available in GWD.
Example: When I try and preview the "MDE 728x90 Expandable Banner Ad" I just get a blank white browser tab in Chrome, but when I preview "In App Expanding Video", it works just fine.
Using a Windows 7 machine
Google Web Designer: v 1.5.4.0113
Shell: 1.2.4.0