On startup, an error message appears immediately over a window where you can type plain username / password, saying invalid username / password. All that is entered in the username field is "f", as if someone were typing "f" and then enter immediately at login. I can then cancel the message and it takes me to the XP user selection screen where I log in normally to the local computer. Where do I begin looking for what's causing this? Any help is appreciated as I'm not as familiar with XP.
Edit: there are no group policy startup scripts configured