Recently we have an issue with oscommerce. We were developing an oscommerce site and everything was working fine in our test server. But when we moved to the production server provided by the client it stops working. The issue was we couldn’t login as admin. Every time we logged in with correct parameters it was showing an error “Error: Invalid administrator login attempt.” We were searching for a solution in the google but nothing helped us. Later we found that we cannot even login as users and cannot register a new user also. So we have done some debugging and atlast what we got the solution. The issue with the domain name and the one which we gave in the configure.php. The domain name always show with www. ie, when we type http://mysitename.com it will show as http://www.mysitename.com. What we gave in our configure.php file was http://mysitename.com. So issue with generating cookie and also POST information. When we changed the value of configure.php from http://mysitename.com to http://www.mysitename.com, it began to work. Hope it will be helpful for some others also.