That seems to have fixed the issue! :)
Just to clear things up: if you keep being thrown back at the login page, your cookie security level is too high.
Here is to lower it:
Click on extra -> Internet options, go to the tab Privacy, and then click Sites(or websites, I'm using dutch IE 7), and add your site to it.
Afther those steps it should work, because your browser doesn't deny the cookies anymore.