Rgistry growth

We have about 2000 DUN connection via DHCP to different clients per
week. It seems that all those connection are registered at
HKLM\SYSTEM\CurrentControlSet\Services\Dhcp\Parame ters. This is causing
a dramatic registry growth that causes a boot failure because of
<windir>\system32\config\system failure.
Does anyone know how to restrict the growth of that key or how to
forbid the storing of that DHCP information?