I think I found an answer to my own problem. I had previous difficulties changing a prior password. During correction of that, I set a password for both the complete site and the same password for my home page. Thus, when the user entered the password to get to my site, they were taken to my home page - which also expected a password (the same one). Clearing the home page password cleared up that issue.
Also, the problem with copy and paste was probably because the users are inadvertently adding a space at the end of the password when copying - thus making it an invalid password.