Remote Desktop "the username or password is incorrect" error?

Question

Suddenly, I was not able to do RD to user1 and found out the PC (win7) I am trying to RD was power off.
I still cannot RD to user1 after started the PC with "the username or password is incorrect" error.
I can RD to user2.

-Verified the password on user1 by physically logging-in and the password was accepted.
-Deleted user2 to directly log in to user1: Failed with "the username or password is incorrect".
-Set up user2 again and was able to RD to user2 but not user1.
-Changed passwords for user1 and user2: user2 can RD,user1 still cannot RD.

Please recommend solution, Thank you.