Valid URL was not provided.

I just updated a the WordPress network I have at http;// The update went fine on the main site, but when I tried to update all the associated sites, I got this error right away: "Your server may not be able to connect to sites running on it. Error message: A valid URL was not provided."

I reinstalled the update to no effect.

The first time I tried to run the update script, it hung on a spam blog that I have since deleted: It hasn't reported a specific blog since then, just the message above.

I have my host checking into it, but I don't know how I would give them anyway to recreate the error. Is there a log file that might garnish clues?