I had the same problem, and someone here suggested these steps and they worked for me:
1) Edit the settings of the VM, and change the close behavior to "Shutdown" (only required if your VM isn't shut down currently).
2) Open your VM, and if you can click on the Shutdown button at the login window, do so - pick Restart.
3) Continually hit F8 as it is "rebooting". If you do it right, you should get the usual Safe Mode boot choices.
4) Pick the first choice - Safe Mode.
5) At the login screen, type in Administrator for the username, no password - you will log in unless you purposefully somehow set a password on the Administrator account. If you've forgotten this password - you're going to have to use special programs to recover the password which I won't cover here.
6) Once logged in, go to the Control Panel and select Users & Groups. Click the XPMUser account and select Remove Password (or you can reset it - up to you).
7) Reboot once again (don't forget to change the settings for the VM back to Hibernate)