On my Adsense Site Diagnostics page, Google lists my domain as a "blocked URL" with the reason being "multiple errors" on Friday

There's been no noticeable change in my CTR or anything else.

I monitor the site, and it had no downtime that day. The DNS is set up correctly (non www points to www, etc) There's no problem with the robots.txt file.

Anyway to get more info than "multiple errors"?