Seller suspended from Audiogon...

I am following a couple of preamps for sale by members. One was a Primaluna that was a bit over my price. However, the owner was kind enough to answer some questions. The seller had good feedback for previous transactions. I was browsing today and saw the amp was not there and looked up the member. Now it says "suspended" by his screen name. Just curious, what are the general reasons people get suspended on Audiogon. Looks like he had a good selling track record in the past. Just curious