Thumbnail Image in Media Libruary

I have set up 3 different multisite test-platforms and installed multi-db on each platform, and since then when you upload an image to the media libruary using the multi-file uploader, or the browser uploader, the thumbnail image in the libruary displays the default image which originates from this link: wp-includes/images/crystal/default.png

If you add an image straight from a new post, the right thumbnail appears.

Is there any way in which I can rectify this to ensure the correct thumbnail for each image is displayed?