IE Login Issue (Login page redirecting to itself)

Hi,

We have a login page in our website named Login.aspx, whenever a user enters username and password and clicks on submit button the user is again redirected to the login page itself.

The status in the page header changes to Logout but the user is redirected to the login page again.This is only happening in IE browser and specially IE8.

After the site is added to Trusted site zone list everything works perfect but if the site is not added to Trusted site zone list then this issue arises.

The website uses a trusted valid SSl certificate then there should be no point of adding site in to Trusted site zone list.

Any Idea guyz ????