Unable to login in ASP.NET based website on Windows Server 2008 R2

Question

I'm using Windows Server 2008 R2 after XP experience. In my one of the website when I enter the login name and password the login page is just simply refreshed and the entered login name and password disappear as if nothing had ever been entered. Have you ever heard of other users getting this kind of problem?

When I recover password, in email same password available. I am using Internet Explorer and Google Chrome but both has this difficulties. In my another XP OS PC everything is good. I think no any browser based issue because today in the morning Chrome appears good to me and I worked on that site. After 1-3 hrs Chrome and even Internet exp. both strange me.

Strange for me!!