This isn't exactly related to shops, but I've been experiencing the strange half-dc issue since the start of new source so it's probably nothing caused by another character. If I afk'd in a map for probably longer than 30 minutes, I'd even be able to walk around the map, jump, and attack once I came back. But if I did anything that required communication with the server (chat, leave map, use items, use skills, etc) I'd immediately disconnect. I assume the same thing is happening to some of you folks with stores.