I've been able to reproduce this several times on my Nov 2007 MBP 15". After the SL 10.6.2 update is applied when I reboot I get a wider and larger then normal white Apple on a grey background with a spinning progress indicator telling me the firmware is loading. It then goes to a black screen and NEVER returns. If I then boot the MBP in target disk mode, take my old PowerBook 12" and use it to run Disk Utility, Repair on the MBP drive it will find nothing wrong. Now if I then restart the MBP is boots with a normal sized while apple, blue screen then everything loads normally. At that point I've used the system for as many as 30 days, or as few as five minutes, reboot and I'm back to the large fat apple logo then a black screen. This ONLY happens after 10.6.2 is applied. I've confirmed that 10.6.0 is fine and 10.6.1 is fine. It is most definitely something in 10.6.2, likely a very low level file whose permissions are being corrupted and as soon as the firmware starts initialization it checks for this file prior to even putting up the white apple. I've even cloned my 10.6.2 MBP drive, did a disk repair on both the MBP drive and the firewire clone then after starting up then rebooting on the MBP drive I can't even get to the boot drive select screen to pick the external firewire drive whose filesystem is clean. If I then run Disk Utility, Repair on the MBP drive I can then restart, drive select the external drive and it will restart. Is there a hibernation file or something in the 10.6.2 image that might be corrupted or have invalid permissions?