About every minute or two my chat keeps saying Joined channel "Guild", Joined channel "Officer" and Joined channel "Zone". My friends also tell me that at the time i see those in chat there chat says that i went offline and back online instantly. I have typed /net_graph 1 in chat and my latency stays around 70ms. I have also did a packet loss test with google.com and sent them 5000 packets from the command prompt and the results are 0% packet loss.
Check to see if you are using one of the proxys in the launcher settings. One of my friends was having the same problem as this and he was using the EU proxy, he changed the setting back to "none" and the problem went away.