ORA-01017: invalid username/password; logon denied
Cause: An invalid username or password was entered in an attempt to log on to Oracle. The username and password must be the same as was specified in a GRANT CONNECT statement. If the username and password are entered together, the format is: username/password.
Action: Enter a valid username and password combination in the correct format.

http://download.oracle.com/docs/cd/B28359_01/network.111/b28531/authentication.htm
•Enforced case sensitivity for passwords. Passwords are case sensitive. For example, the password hPP5620qr fails if it is entered as hpp5620QR or hPp5620Qr. In previous releases, passwords were not case sensitive. See "Enabling or Disabling Password Case Sensitivity" for information about how case sensitivity works, and how it affects password files and database links.