Hi, PageRank is a link analysis algorithm. If you have added low quality links there is a chance for your site's PR to go down drastically.Also Google is changing its PR algorithm often. Hence, keep a track of the changes in PR algorithm and update your site accordingly.
Damn, maybe I got penalized by G. I don't know why though. I don't sell stumbles...I checked a few others around and they had no PR either. Maybe it is just a matter of time before "pal" is sad
Try double checking the pr on dnscoop.com and similar sites that report pr. It's possible that whatever resource you're checking the pr on now is simply not working correctly. Remember that google toolbar pr only updates every few months and is probably still a few months away from the next update.
It is the G toolbar that I'm reading. And it happened within the last month or so. I am fairly active with my account.