I'm also experiencing this error. I made an observation and these are what I seem to found:
1. The error occurs wherever you are in the game (Town, Field, Dungeon, Nest, Login Menu, Character selection, etc.)
2. The occurence of the error is quite relative with time (how long have you been logged in) or until the program itself, Dragon Nest, encountered the error. This is what I observed when I played Nightmare Stage where the error occured at stage 3 where it took us a while to get along because of the boss rush but we didn't managed to finish because of the error. Also, I tried to login another character and standby in Merca's Heart then it was roughly 15 minutes, the error occured. I tried it again but I wennt standby in the Channel Selection part upon logging in your account, that was roughly 18 minutes, the error occured again.