One of my sites was banned for close to a year. It just got unbanned a few weeks ago. I had a PR 4 on all content pages and 5 on the home page after I was unbanned, which was what I had before being banned I think. It had been as high as a six. The home page PR sort of came and went, it wasn't constant. But the other ones were. Well, now I have a constant PR of 5 on the home page and none on the other pages. I do have reasonably good placement in the index. Not great but good. What might be the reason I have no PR on the other pages?
Is your internal linking up to scratch ? I know it not quite the same but I have had almost the reverse before where the inner pages were PR5 and the home page a PR4 , that was internal links. Also check your site map and your webmaster tools. Best of luck
too many links exchange or fake SEO site can lead to this, there are many reasons, sometimes Google do it because they "want to"