This is kind of a weird problem. Not seen it before I made the switch to 64 bit Vista but the latest version of Yahoo Messenger crashes ONLY when I try to message someone connected to the internet via my router. Like my 2nd PC and my wife's laptop. As soon as I start typing a couple of letters it just crashes. I can talk to anyone else for hours with no problems but as soon as I try to talk to my wife or my nephew it crashes. But they have no problem talking to me. If they send me a message I can get it and it doesn't crash but I can't type back to them.