Thanks for the link. While it has some good information, I don't think it applies to my problem.
"Hybrid Sleep" is already turned off
Also, I've tried disabling audio, wireless, lan, DVD, USB ports, all I/O ports, etc. Also tried swapping drivers for video, synaptics touchpad, and wireless. I have the latest BIOS.
One thing to note, after it resumes from hibernation, the hard drive appears to have pretty steady activity until the machine locks up (approximately 60 secs).
What else to try?