From the bug report available on the release history page:

Defect: Thumbnail images appear below treeview

Issue Detail:
In some browsers (such as IE8), the thumbnail images appear below the album treeview, not to the right of it. This applies only when the treeview option is enabled on the Gallery Control Settings page.

Resolution:
The fix was to modify the CSS. The old CSS:
.gsp_floatcontainerWithTv {overflow:hidden;width:85%;}
The new CSS:
.gsp_floatcontainerWithTv {overflow:hidden;width:85%;margin-left:15% !important;}

The file is gs\styles\gallery.css. Hope this helps.