Not sure if this is the right forum section, but seemed the most appropriate.
I have a very highly ranked site, ranks for many terms on page 1 as well as its main KW, which is pretty competitive, has 100% all natural links, absolutely no manual link building, except for some initial article promotion over a year ago, it's a blog in a very competitive niche.
The site had a homepage PR3 for many months with PR1-3 for many inner pages, and then suddenly went to PR0 sitewide and has stayed there for the last 3 updates. Rankings still in tact, and rising regularly, I can publish a post and it almost instantly after crawl goes to page 1 for the search term, but no PR change whatsoever.
What are the reasons this could happen? I have never sold links, and the blogroll is very small with all legite sites.
The blog is dofollow in comments, but I know that's not it, as I moderate comments and I have many friends that are dofollow comments as well with PR4 and PR5 sites.
A while back I did do some link exchanges, where I got a few links to my other sites in exchange for placing their links in existing inner posts on this site, a total of about 6 links on inner pages with PR. I suspect that Google may think I am selling links because these links popped up on existing pages as opposed to fresh content pages, but unsure if that is the reason?
Does Google think I am selling links, as that seems to be the main reason I have found in researching this topic for loss of PR?
Anyone have any wizdom to this issue?
I care more about the ranking overall, but I am really curious as to what is going on and how to possibly fix it?!?