Problem solved! On a whim, I reinstalled the NVIDIA 6150 drivers that came with my ASUS M2NPV-VM motherboard w/ NVIDIA GeForce 6150 integrated video. Hibernate now works again. So, the Microsoft Update drivers for the NVIDIA 6150 are not appropriate for all 6150 owners.
Hello Joemoe38, Did you ever find an answer to this problem? I just got bit by the same problem about a week ago on my Windows XP3 system after using Microsoft Update to get the latest NVIDIA 6150 drivers. Now neither hibernate nor stand-by works - same result as yours - black screen with thin blue line on top. Rolled back the drivers too but that did not help.