Kernel-mode drivers have access to system-wide memory and poorly-written ones can cause STOP errors.

The system behavior towards kernel-mode print drivers is controlled by a Group Policy Object:

Windows XP

Local Computer Policy / Computer Configuration / Administrative Templates / Printers / Disallow installation of printers using kernel-mode drivers.

If you enable this GPO, the installation of kernel-mode printer drivers will be prevented.

Windows Server 2003 family

Local Computer Policy / Computer Configuration / Administrative Templates / Printers / Disallow installation of printers using kernel-mode drivers or
Default Domain Controller Policy / Computer Configuration / Administrative Templates / Printers / Disallow installation of printers using kernel-mode drivers.

If you do not configure this policy, the installation of kernel-mode printer drivers will be blocked.

NOTE: If you enable this policy and kernel-mode drivers are already installed, they will be disabled the when you install a service pack or perform an in-place update.

NOTE Kernel-mode drivers cannot be installed on Intel 64-bit Itanium computers.