First a fact: You cannot set up Windows XP Mode without a password for the default user account XPMUser. Installation stops here and does not let you to continue without setting up a password:
(Screenshot from this tutorial, step 7: Windows XP Mode - Install and Setup
I am not fully understanding what your second post means, did you solve your issue? At least it seems that your XP Mode credentials are username XPMUser
(if you have used the default user account created when installing XP Mode), and password is "Password
To force XP Mode to boot from scratch when it is hibernated you need to manually delete the saved hibernation data, the file Windows XP Mode.vsv
which is stored by default in C:\Users\Your_Username\AppData\Local\Microsoft\Windows Virtual PC\Virtual Machines
Deleting the hibernation data forces XP Mode to boot normally as if it had been shut down last time instead of hibernated.