Symptom: When a user attempts to Login to the system using a valid username and password, the user is not able to proceed past the Login form. Upon submission, the Login form simply appears repeatedly without any error message. At the same time, if an invalid username or password is used, the Login form displays an error message as expected.

Cause: This problem is caused by the Login mechanism not being able to set and persist session variables. In order for the Login to work correctly, it must be possible to successfully create session variables. The Microsoft security patch MS01-055 prevents servers with improper name syntax from setting cookies names. Session variables rely on cookies so if cookies cannot be created, it will not be possible to create session variables and therefore the Login mechanism will fail.

Resolution: Please refer to the Microsoft article http://support.microsoft.com/default.aspx?scid=kb;en-us;316112 for information on how to resolve the problem.