In Windows 7 there is an option called "Always show icons never thumbnails" and if this is set you see the flower icon and not a thumbnail of the photo.
This is how to change it.
On the "Windows" menu select Computer on the right.
On the set of menus at the top select "Organize" and from the Organize menu select "Folder and Search options".
From the Folder Options window sect the View tab.
On the View tab, at the top of the Advanced settings, deselect (no tick) the option "Always show icons never thumbnails"
Save changes and that should fix it.