XP Controlled by another program…cannot boot to windows

We downloade a business program and every time it boots up it goes to that program asking for a password. We have tried all types of passwords, but have no idea what was entered.
Now that it controls the computer, we cannot get it to reboot in safe mode, setup, or anything. Is there a way to override this program and go to safe mode to make corrections?
Tried putting in an XP Pro Disk, but it will not boot from the CD. Any suggestions?
rvndoc@netscape.net