The Toolbar PageRank value only indicates that a page is in a certain range of the overall scale. One PR=5 page could be just above the PR=5 division and another PR=5 page could be just below the PR=6 division, which is a vast gulf

Although the exact logarithmic base used for PageRank is a secret, the following
table should give you an idea of how different Toolbar PR is from actual PR.

    Toolbar PR (linear) Actual PR (log base 5)            Actual PR (log base 10)
              0                      0.15                            0.15
            0-1                     0.15 - 1                        0.15 - 1
            1-2                      1–5                             1 - 10
            2-3                      5 – 25                         10 - 100
            3- 4                    25 - 125                      100 - 1,000
            4-5                    125 – 625                    1,000 – 10,000
            5-6                   625 – 3,125                  10,000 – 100,000
            6-7                 3,125 – 15,625                100,000 – 1,000,000
            7-8                 15,625 – 78,125             1,000,000 – 10,000,000
            8-9                78,125 – 390,625            10,000,000 – 100,000,000
           9 - 10                  390,625 +                     100,000,000 +



This means that moving a page from a PR = 6 to a PR = 7 is much harder than
moving from a PR = 4 to a PR = 5.

Although PageRank is assigned per page, your site is a collection of web pages
under a domain that you control and hence your site has a total PR value too.

PR as viewed using the Toolbar can be pretty inaccurate. Sometimes home pages
for sites will suddenly show a PR = 0 (no green bar) when indeed the page does
have a PR value. Appending /index.html to the URL (or whatever the filename is for
the home page) in your browser restores the proper value displayed in the Toolbar.

Also, new web pages that the Toolbar displays a PR value for may not have any
“real” PageRank of their own yet. Rather, the new page is “assigned” a PR value 1
point below an indexed page on the site, but this is an “estimate” PageRank that
exists only in the Toolbar.

My suggestion is to simply ignore that little green bar. It never was that accurate to
begin with and it’s just gotten worse over time. It really doesn’t have much bearing
on how well you are ranking.