Screen goes weird when msn comes up

Hello,
i have had the new windows live messenger for a while now and things have started to go wrong. it wouldnt let me sign in at first so i deleted it and downloaded it again. now everytime i open windows live messenger the screen goes blank then it goes all weird colours and it wont let me sign in then when i exit windows live messenger it goes back to normal. sometimes when it does that i let it sign in for a while but it doesnt repond when it is doing that then it says something like windows connection platform is not working. i dont know why it has done this and its really wierd!
please help!