I have KM running on my desktop right now and seems to be working fine for me, no one else is on however. I played Mayo Chiki - Be Starters through it and it worked fine. I didn't sing, because, I don't lol. For some reason I couldn't send anything to the chat, not sure what's causing that.
Make sure you choose server US 1. It should be the default.
Also just a quick note for anyone who has Norton, it might delete the file claiming WS.repuation.1 - that's Norton speak for 'it doesn't have any reputation' which of course it wont have. Just disable Norton for 15 mins then re-download if you have this issue.