1) Use Firefox. IE, Chrome and Safari have issues
2) Confirm that the SIP boot server hasn't changed the admin password (Contact Human-ISM support. Administrators can check the phone's admin page for a changed admin password).
3) If all else fails unplug power, hold 1, 3, 5, & 7 keys while powering up, then enter MAC address as admin password (press # to switch from numeric to alpha entry), which will reset password to default. Will need to clear settings and reprovision phone for extensions.