Found on several systems after installation of GeForce drivers 169.x to Visa SP1 64.
After Vista boot screen with animated green line screen goes black and monitor turns to power saving mode while system seems continue loading. This nasty bug appears only (?) on 8800 boards.
The only way to see your desktop is unplug DVI cable from video board and plug it back again. This will happens every restart. Hope nVidia wil fix this in next release!