Can someone help me with my Battlefield 2 online problems?

first of all, singleplayer runs perfectly and smoothly. alright, here are the problems. first off, i have a pretty normal internet connection. but, i have mive lag when i join a game. but sometimes, i don't even get into the game. sometimes, when i join the game, it either just crashes of it says something like punkbuster handshake. please help.