I am able to login to data loader for production instance however I am able to login to sandbox. I am adding the security token at the end too. I am using version 37 of data loader and windows 7.
When I try to login into data loader, I get a login error "Error:Check your username and password. If you still can't login, contact your Salesforce admin". I am sure that I am using the correct username and password. I am also adding security token at the end of password.