Umbraco CMS - keep getting logged out in ie, safari, chrome but not ff

I have a few Umbraco sites running on my server - but i'开发者_开发技巧m getting logged out when using everything else than Firefox when using umbraco.

I'm able to log in and after 10-15 sec's i'm being automatically logged out again.

How can that be and how do i fix it? :(

It's a win 2008 server using MSSQL database and umbraco 4.0.3 btw is running on integrated app pool and .net version 2.0.50727

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It was the server time that was 24 hours of - solved :)