BSNL broadband - Unable to connect to messenger

Hi,I have got a BSNL Dataone broadband connection last week and ihave a problem connecting to Yahoo messenger. I tried changing the conection preferences to 'No proxies', 'Firewall with no proxies' , 'No network detection' without any use. I am facing the same problem with all chatting messengers like MSN, ICQ, Rediffbol. It throws me out asking me to check whether i am connected to internet or not. But iam able to browse thru all web pages. The problem is only with the Messenger. Any experts there who can helpme out in this?OS: WinXPIE 6.0Dataone connection 256 Kbps - Home 500Thanks in advance,Sam