I recently faced a problem, where for some reason website would not remember session data for some users. They Log in, get to the home page, but the moment they click any other link they are logged out and taken back to login page.
Interesting thing is, this happens for both Firefox and Internet Explorer.
When I used the users credentials I was able to log in perfectly on my machine. When I passed him my credentials to try, and it failed on his machine.
Please provide any solution to this problem