Open up Firebug (or equivalent) and examine the HTTP request for the image. Does that show you an invalid URI for the request or give you any insight into why that image isn't loading?
This is what image is currently pointing to:
<img title="motivate_90x" alt="motivate_90x" class="cq-dd-image"
It should point to
Have you customized this component at all? I'm not sure why it would behave like this if you are just using the foundation "Text and Image" component.
Which version of cq? Dialog does not looks one come with OOB like additional tabs Advanced properties missing.
Is all the pages with image having this issue. If so make sure the bundle org.apache.sling.scripting.java exists and running.