Weird Issue with IE6 regarding session

Hello, i got a weird situation regarding IE6 and don't know if the problem is on Rails itself, on IE, or on our own Sharehosting but the problem is like this : There r user trying to login to our site and it's successfull getting into user private page but when the user click "something" link that use AJAX call, suddenly it's fair and nothing happen anymore the page just static and neither of the links in the private page work... but... the strange thing is suddenly all "user" just can't login using IE6 (but it works on FireFox), it just when the user submit the login button it always redirect to home again although the login name and password success and there is no error on rails log or any the page just throw back to home everytime a user try to login.... and it happen about 1 hour approximate after that everything suddenly just back to normal..... I'm already got this problem twice and until now still doesn't have any clue bout what's wrong..... Does anybody has the same issue as me ? I'm using Rails 2.2.2 Thanx