Microsoft Office Sharepoint Server 2007

Hi,
I have installed MOSS2007 on windows server 2003, after installation my sharepoint central admin site asking for authantication. countinuesly prompting username & password. when i esc. that window for 3 times my central admin starts working. when i click operation, again asking authantication and again i esc for 3 times it starts working. please guide me for this problem.

thanks
jignesh