It's quite sad and annoying, but Zemhost have closed their hosting due to attacks. The datacenter said they can't manage the attacks that Zemhost are getting, so they refused service.
Zemhost forums will remain open. They do have a paid service as well though, www.supremebytes.com and the hoster of that said they won't deny service due to attacks. If you were a member of Zemhost, you can get the second and third month of hosting at Supreme Bytes free.