This is very normal for any Chinese website with forum and open for registration.
Some one, e.g. scammer, spammer and competitors, use bot or human power to register whole bunch of accounts, and put a lot forum posts that contain so-called sensitive contents on your forum.
If your spam filter is not smart enough, or your admin groups are not fast enough on handling these, or some one just reported your site on purpose, your website will eventually be caught by the big brother.
As a result, the big brother will send you a letter saying your plug is pulled until a certain date. At the mean time you should clean your mess and promise similar thing will never happen again.
