Since a week I lost my stable pagerank 5 for one of my dutch websites. I had that pagerank for almost a year till then. My first thoughts was a Google penalty, but the only thing I lost was my pagerank, my SERP is still very good, and I'm gaining still the same amount of google visitors. From pagerank 5 to pagerank unavailable. Also some innerpages lost their pageranks, some don't. Any idea why Google should do this?
First you are always up and down. Google changes your PR or keeps it on each update. Think about all those mature/strong sites that you've visit one year ago, check there PR now, half of them have changed. It depends on how much you work.
Check your backlinks, PR always got to do with backlinks, maybe some of the pages linking to yours are downgraded, or some link to your site been deleted. Naither PR and SERP are supposed to be stable. Internet is dynamic.
This may be a temporary effect if there is "PR unavailable" rather that some definite value like PR4 or PR3 etc.
Don't get too concerned about PR. For as long as your ranking/SERP remains the same, there's nothing to worry about. You're doing fine.
No changes in backlinks.. I have multiple pr5 and pr6 backlinks, besides that loads off pr4 and lower backlinks. I'm not concerned, but I'm wondering why Google should set my pagerank to unavailable if I have such strong backlinks. Pagerank n/a is nothing. If my pagerank went from 5 to 3, I shouldn't have this topic opened, the n/a is just weird.