No his PR is 0. right now... Google toolbar and SEOquake both shows 0. Well don't worry in next pr update it may be come with PR 5 also. May site has expirienced the same in last update. I really want to suggest u just make back links, and try not to place any more adds and banners on the website. Best of luck. Bloomtools.
I've checked my all the sites, From my side, No changes and No Bugs in SERP. Everything is Alright, just keep hard work in quality links with targeted keywords. and Don't create Bad neighborhood with spamming links or paid links. John