Replace the links to images in the form
href="/images/file.png" (add a leading slash and the full path to the file) to fix the problem.
By the way, the thread title is misleading. Google didn't "change" your URLs. When Google accessed those incorrect URLs (from a link they found somewhere on the web, either on your site or on some other) a design error on your site meant they returned 200 OK and were therefore indexed.