This blog had a PR of 3 a while back. One day I got an offer to put some links from a company called ZTMC and they would pay me monthly for posting those links. I never expected this blog to make any money so I agreed and posted the links. A few months went by and suddenly ZTMC cancelled my subscription. I discovered that the PR of this site went from 3 to 0. I can’t say for sure that it was caused by the Ads but it is very likely. I saw another posting online reporting a similar case and also Google’s terms and conditions frown upon paid links.