I'm having major headaches with one of my DNN sites. It's a standard DNN 5.02.02 installation with no modifications to the core DNN. There are some custom modules developed internally as well as some other modules from SnowCovered.

The site has over 8,000 active users and recently some of the users (including the administrators) are having problems logging in.

The user enters their correct username and password on the login page and immediately get redirected to the home page without being logged it. If I check the Log Viewer in the DNN Admin menu immediately after this action, I can see the user in question has a "Login Successful" message. There are no error message, exception or anything out of the ordinary. The user is still not logged in though!

This problem is intermittent and I haven't been able to figure out a pattern to it yet. It happens to some users more than others but there doesn't seem to be any relationship between them or the browsers they are using.

Usually clearing all cookies on the browser will fix this - this is fine for administrators but not for regular users.

I'd really appreciate some help on this as it's becoming a real problem for us.
Thanks!

Thanks for the reply Chris.

Yes - I have one other site running on a sub domain with separate login credentials. But the user base is separate - I'm sure of this.

I have this entry in web.config:
<httpCookies httpOnlyCookies="true" requireSSL="false" domain="mydomain.com" />