After returning from Sleep or Hibernate on my Windows 7 desktop machine, I noticed high CPU usage on one of my cores. After tirelessly searching Google for a possible solution, I was unable to find one and wanted to publish the solution to my problem.
Utilizing Process Explorer, a tool developed by Microsoft which provides detailed information on running processes such as CPU utilazation, I discovered that the consumption was occurring in ntoskml.exe (I can't recall the exact method). This suggested that the culprit was the windows kernel, such as a driver module--not a rogue process.
To further debug the issue, I launched,
from an elevated command prompt that generated an interesting report on my systems power management. Of particular interest were several errors associated with the USB subsystem. This crucial piece is what lead me to my solution.
It turns out the culprit was an old driver for my Creative Labs SoundBlaster X-Fi Surround external USB sound card. Updating to the latest drivers, found here, resolved my high CPU utilization problem. Good luck.