My site's been around for over 4 years and has built up a great page rank on many pages (between 2 - 5, average PR 3). I pride myself on my SEO skills and have applied all tricks - good links, 301 redirects, canonical links etc. taking care not to duplicate content etc etc. (mostly using the Ifinity tools). Traffic is at an all time high (1300 uniques a day from organic search). I use sitemap and Google webmaster tools (no more errors than usual)

However, an advertiser cancelled citing that my PR had dropped to 0 on my blogs page (http://www.pokerdiy.com/poker-blogs.aspx) which was a PR3 this year and a PR5 before that. My home page has dropped from 5 to 3 so I decided to dig deeper....

It turns out that a massive amount of my pages have dropped to 0. Now it may just be a cosmetic thing - I tried 10 different PR checkers on Google and one of them shows the correct data:

http://www.build-reciprocal-links.com/pagerank.html

These ones don't (and about 10 others I tried from Google - the majority):

http://www.iwebtool.com/pagerank_checker?domain=http%3A%2F%2Fwww.pokerdiy.com%2Fpoker-blogs.aspx

and the Google Toolbar does not (but works fine on other sites).

Here is a list of pages that I know were PR3 6 months ago (they were on my ad list) and now they are all 0!!!

http://www.pokerdiy.com/faq.aspx
http://www.pokerdiy.com/watch-poker-videos.aspx
http://www.pokerdiy.com/poker-blogs.aspx
http://www.pokerdiy.com/find-by-map.aspx
http://www.pokerdiy.com/add-poker-widgets.aspx
http://www.pokerdiy.com/poker-rss-feeds.aspx
http://www.pokerdiy.com/about-pokerdiy.aspx

http://www.pokerdiy.com/school/poker-quiz.aspx

Any suggestions please? Could it be something to do with the Google spider? (the cached view is showing fine).

Entrepreneur

PokerDIY Tournament Manager - PokerDIY Tournament Manager<
PokerDIY Game Finder - Mobile Apps powered by DNN
PokerDIY - Connecting Poker Players

Rodney : It's somewhat of a million dollar question this one, but I'll take a stab.

Firstly, PR is immensely devalued, and I like to think of it as a bit of a magicians white glove : being waved about to keep your eyes on the PR score and away from what's really happening, which is rankings and traffic.  I know you've checked it with other sites and aren't relying on the Google toolbar, but the most important thing is rankings and not PR.  Are you getting less traffic?  Have those pages ranked lower for previously well-ranked search terms?   Is your search traffic affected in any  way at all?  This is more important than PR for you as a site owner (advertising buyers notwithstanding)

On the other point, the Google terms of service expressly state you shouldn't be selling/buying links.  Leaving aside the whole discussion about this and how it applies to adsense : is it possible you have been penalised for selling advertising by way of links? Clearly your ad inventory buyers are keenly aware of your PR where their pages are located.  Is it possible a competitor has reported you for sellign links, and has resulted in you being penalised in Google?

I doubt this is an indexing problem, you can double check by scanning your logs and looking for the Googlebot and seeing if the frequency has dropped off, or if it has been receiving 404 errors or anythign like that.  Similiar info will be available from the Google Webmaster tools if there are crawling errors.