Big mysterious problem !

[Blofeld]

I'm experiencing a strange problem with 10.1.3 from time to time.
with no apparent reason I'm unable to use my root and/or user password.
when I go into Terminal there's just the prompt"password:" but it does not recognize my passwords anymore,; even the su/root password.
The problem can only be resolved via restart...

Any suggestions what it could be ?

[Blofeld]

Problem still persists...
any suggestions ???

[scruffy]

Can you still log on as normal to the computer, or does it automatically log you in without asking for a password?

Have you checked the terminal's preferences, especially the Shell section?

What about if you log out when that happens - can you log in again? what about if you log in as >console with a blank password? can you then log in with your username and password?

[Blofeld]

I tried to log out but it won't accept any known passwords on login also >console does not work.
Only a restart brings everything back to normal...