Anyone having disply problem with yahoo messenger?

I have sbc yahoo and I'm using Yahoo Messenger (beta) 7.0.0.242 for chat. My dosplay is and has always been set to 800by600pixels. Everytime I go online and click messenger it takes up the entire screen to the point that the only place I can grab it from is the top and drag it down.So I have to open control panel, disply, settings and set it to 1024by768, sometimes at 1152by869. Then I can go back and grab it and pull it back to normal.Then reset settings to 800by600.Its simple enough to do but I'M REALLY GETTING SICK UP AND FED WITH DIS CHIT,MANG! Anybody having the same trouble or know how to fix it? All help appreciated. Thanx eah