The broken link checker simply observes the http status code that the URL returns when we test it. If it's 400 (bad request), 404 (not found), 500 (internal server error) we consider the link to be broken.
It looks like many of your broken links were amazon links. Most likely they had some technical issues that caused those particular urls to return 404 for a time. You can go through and retest them on broken links page yourself, or just wait. They should clear up on there own over the next few days (we try and test every broken in a published hub every 7 days).
I've had the occasional link here or there that was mis-marked as bad. But your situation sounds like a lot of them -- unless they're all to the same domain and it's gone down. Why don't you drop a note to email@example.com.
This is a great feature HP has...flagging Hubs where links within those Hubs are broken.However, just in the last 20 minutes, four of my Hubs showed on My Account page as having broken links. Only one did. (As in, there...