I noticed last week that my Google pagerank had dropped from four to zero. I assumed it was something to do with shifting my blog from the domain root to a directory.

That’s probably the case, because the Google webmaster guidelines state: “Don’t create multiple pages, subdomains, or domains with substantially duplicate content.”

I suppose while the robots were crawling the new blog they still had records of the old one and a computer determined it was a duplication.

Google is still indexing my site. I have submitted a request to have the zero ranking reconsidered.