I just resubmitted the skin file, so hopefully the download link will work now.
The issue seems to be that only the edges of the toolbar background image are painted on the toolbars in IE and Explorer. It's not just you, this is happening here as well. In other apps with toolbars, such as SkinStudio, the toolbar background paints correctly. I have no idea what's causing this, but it seems to only happen with WB5. My laptop is still running WB4.6 and it doesn't have this issue.