Hi, I put co-op ads on all of my sites around the latest PR update. It went well, and then a couple of days later, 3 of my main websites have mysteriously dropped from PR2 to PR0. The sites have a lot of backlinks, and in no way deserve PR0, so I've completely scrapped the Co-Op Network in case it happens to the rest of the websites. Is there anyway to contact Google about it to confirm it was the Co-Op Network?
Using tools like the Co-op ad network is against Google guidelines so it could be the cause, no way to know for sure. You could do a re-inclusion request with Google and hold your hands explaining what you did wrong and that you won't do it again.
Sites drop regularly with google , its good to make sure its the CO-Op before you contact google. Your problems could be due to other reasons.
I really don't think it can be against Google's TOS or otherwise sites like moneysupermarket.com would not rank where they do for such ridiculously competitive keywords. I realise Google can hardle keep track of every site on the internet but I'm sure its aware of the ones that rank in the top 5 for the most profitable and competitive keywords in the world.