Due of changing of password, its necessary to download xrumer_key.txt file again. Place the file in main folder of XRumer.For changing the password in XRumer:
1. Close the program, if its running.
2. In xuser.ini file delete [User] section
3. Run the program and enter your new password.
We apologize for any inconvenience.
it's from botmasternet.com
2 days ago was made message on Xrumer's official forum
http://www.botmaster-forum.net/showthread.php?t=1647