Errors (in their simple form) mean exactly what they say. If in fact your clients passwords have not changed, somehow the script isn't properly communicating the username/password to the server. You should troubleshoot the issue more before going any further.
Take a problem client - open their script. See if you can login with their username/password that the script uses. If you can't, there is your answer. If you can, double check your script settings. Make sure the address is correct. Make sure that the server that is using the script can resolve the name (or connect to the IP) of the Centova Cast server.
It's not safe to assume the client didn't change their password - always verify it first. I've spent countless hours working on step two because I never checked out step one to begin with.
Also, yes - if you want official help submit a support ticket to Centova. However, I can't see them saying a ton more than what I have. It's not a Centova issue so you will need to troubleshoot to try to figure it out.
Breck Burgess
MyShoutServer
Breck Burgess
MyShoutServer