>When I try to login in from Internet Explorer, the login fails. Chrome works fine. Happens on multiple PC's.

Have you upgraded to IE 8? We have observed some very stange behaviors and an unnecessary amount of excessive security with that one. That might be a factor. As for me, either with 7 or 8 works fine. This can also be related to third party software that interferes with the good running of Internet Explorer. See http://www.levelextreme.com/Troubleshooting.aspx and let me know if all those points have been verified.