When you install a device driver that Windows 2000 or Windows XP detects as being NOT digitally signed, you receive the the subject message.
The Setupapi.log file may also contain:
E245: The device installation digital signature failure policy has been elevated from Ignore to Warn due to a proposed replacement of a protected system file.
The above behavior happens even when the Driver Signing Policy is set to Ignore.
Windows automatically raises the driver signing policy from Ignore to Warn because Windows File Protection is programmed to promote stability of the operating system, and an unsigned driver may cause instability.