It sounds like you have turned the security when you were using it from winXP computer.
If only you are using it and do not need to enter password.
I would suggest you remove the password.
Here is how to do it:
From the WD Smartware menu click on Settings
Click on Drive Settings
Click on Security
Under the Password enter your old password
Make sure that Remove Security is selected
Then Click on the Update Security Settings
That would remove the password.
Unplug the WD external drive and plug it back in for the new change to take effect.
