Check your Windows Explorer settings. Specifically in the Tools menu, 'Folder Options', 'View' tab. Then DE-select the "Always show icons, never thumbnails". It's near the top of the check boxes.
I had this problem running Internet Explorer 10. Microsoft apparently stopped supporting SVG images after IE9. I uninstalled IE10 and installed an older version of IE. Fixed the problem.
Zack,
Is this set in tools>options>system options?
Show thumbnail graphics in Windows Explorer.