Welcome to the Q&A Forum

The link you provided still works, it's just redirected to http://pro.moz.com/tools/crawl-test

Thanks David, Monica and Lewis for your responses - I appreciate your thoughts - and I love how you all so consistently started your responses with "stop worrying" - you're right of course! I have communicated my discovery to the client and my intended course of action was pretty much as David suggests - run fast and bury those links in a sea of press releases and other high quality organic link-building. Still scratching my head as to where the links came from - but I need to stop worry about that don't I? Thanks again!