I'm running Windows 7 Ult x64 with SP1rc installed the day it became available. My system is a dual Dell i7 with 12 GB of RAM. Beginning Monday, November 8, 2010, after I installed a definition update for MS Security Essentials (1.93.1441.0), all attempts to reboot result in the dreaded Black Screen of Death following login. The only work around has been to power cycle, enter safe mode, and do a system restore. I did the customary edit of HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell when in safe mode. I've applied the http://www.prevx.com/blog/140/Black-Screen-woes-could-affect-millions-on-Windows--Vista-and-XP.html fix--all of this to no avail. M A Reeds MD PhD