I meant to include this in my last post and forgot. I am somewhat concerned about that 404 error that you got first thing in your spider log.
This doesn't have anything to do with phpDig per se, but I found some free link checker software that you might want to use on your site. Just a word of caution though. It consumes bandwidth on your site about like phpDig does, so you wouldn't want to run it every single day. The free version is called REL Checker Lite, and you can download it
here.