This error can occur when attempting to unlock a drive. It could be due to one of the following:
1) The hard drive you're trying to unlock may not be locked at all. If your computer still says that it is locked, try unlocking the other hard drives to see if you get the same message.
2) It's possible that one of your earlier attempts to unlock the drive worked, and it is no longer locked. If a drive isn't locked, an Invalid Exchange occurs saying that the password doesn't work to unlock the drive.
3) Lastly, it's possible that another program might have locked it, if conclusions 1 and 2 don't work. This one is unlikely, but very possible.
4) Use 'computer management' to examine the computer. If the drive isn't initialized, re-initialize and format it. It should be useable again.