I have a PR4 site which was getting 150 visits per day from G and suddenly the visits dropped from 150 to 20s. The site does show up in search when I search for brand name. But when I search for any line in quotes, G says no results found. However, the line in quotes is present in Google cache. So, my guess ... the site is partially sandboxed. I have been doing blog comment spamming (manual and comment kahuna) and free traffic system. My guess (again its a guess) that freetrafficsystem blogs are infected and considered spam by G. I recently went crazy on freetrafficsystem and submitted a bunch of spin articles. And yes, I did spin them a lot ... A warning to other site owners to avoid freetrafficsystem. If you are an affiliate or owner of freetrafficsystem, I know I am not attaching any concrete data to my guess. After all, as the thread title says ... its a guess not a claim. No, I will not mention my domain name.