yin_101 0 Newbie Poster

Can anyone help me. I have a PC and a Mac. On my PC, I can login into my msn messenger but in my mac, I cannot. I originally was able to login in both computers. I tried throwing away the Microsoft folder in the preference and deleting my msn messenger and then re-installing it. It keep giving this window saying :
Sign in to Microsoft Messenger failed because the service is not available or you may not be connected to the internet.