it can be the annoncement, like what they did with the word that pops up all the time when I logon. - "Do not reborn in party"
Besides, it's their own client that crashes, not the server, although I don't know if there are some unusual case that will crash the server too. Besides, there is another reason behind the dc, which is the change of the location where the server is hosted (yes admin told in chat before). The first server before was lag fest. I reckon that's even worst than the dcs because I can't even get myself a hit fest at all, which usually I say, bleh, so lag, leave it for 2 hours.
Anyways, things need to be invest first before saying this cause that or whatever. What we only know now, is the frequency of disconnection. From the user prespective, the client crashes when try to buy the wrong stuff. You cannot just assume that all the dc is related to client crashing.