I have a ASP.NET application (Framework 4 Classic Mode) running with Windows Authentication - it is an Intranet. Impersonation is on. Anonymous is off.
Authentication works perfectly on every user's PC, bar one. This one user is prompted for credentials, entering them and submitting causes the inputs to clear and it prompt again. After 3 attempts there is an access denied message.
I have formatted the user's PC (for other reasons) and recreated their domain account from scratch. The problem is still there. It happens in all browsers from any workstation for this user, but all other users are fine.
There are 3 other sites on the IIS server. One has the same settings, the other 2 are in Integrated Pipeline mode. They all work, including the identical one. Directory permissions (NTFS) are the same for all 4 sites.
The user is in the same AD groups as everyone else. I have recreated her 3 times using both SBS Console and AD Users and Groups, and tried a different user name. No effect.
The intranet is in the Trusted Sites list in IE. Server event logs mention an unhandled exception but no detail.
Does anyone have any other ideas?