I solved it myself. Since my network is not domain based, I use IP addresses to connect. The PC that I was logging into changed its IP address. The IP addresses seldom change, but it did this time. So, once I entered the correct IP adress for the PC, the password worked properly. What had me fooled is that I never received an error message when using the former IP address--the connection window opened up as before, but would not accept the password.
Thanks for your attempts at helping!