Google toolbar has nothing to do with it. You completely changed the information on your site, what do you expect to happen? of course the pagerank will drop you completely changed everything. There are exceptions when changing design on a website, but when it comes to content google becomes real tedious about it. Just build more links to the page and try not to change it. The only time you should change content on a page is probably once a year with a better design to spice things up. (and what i mean is rewriting it if needed or making improvements)
Also you said you had duplicant content before? Can i ask why you did?
To better up sum this up, just imagine buying a new website address with a pagerank of 4, now you add that address to your website. Google indexes the pages, and guess what? your google pagerank drops to zero. Different content , different everything and it just changes everything from there.