Hi all,
I joined this group specifically to post a solution that worked for me.
First off, brief specs:
SAGER NP5973 laptop with an Intel 4965 AGN wireless adapter
Win7 32-bit with 4GB RAM (patched PAE kernel for 4GB memory access)
NVIDIA Quadro FX1600M
I recently experienced a change in CPU behavior --> running at about 10-15% when IDLE. It turned out to be a high latency issue as detected by LatencyMon, which pointed to NDIS.SYS as the problem.
Long story short - I updated ALL hardware drivers, tried all Googled tricks and got NO result. The only thing that had any effect was to disable the AGN adapter --> then the CPU would drop back to "normal (0 to 1% at IDLE).
Solution: I remembered that I recently updated the NVIDIA drivers for my system. I was running Quadro drivers v195.62 and had upgraded to v311.35. I uninstalled the new driver and ran the Standard VGA adapter -> CPU went to normal (0 to 1% at IDLE). I re-installed the new NVIDIA driver (driver ONLY) and CPU went up to 15% at IDLE! I then re-installed the OLDER v195.62 NVIDIA driver and all went back to normal (0 to 1% at IDLE) ! I don't know why but in *my* case, although things pointed at the AGN drivers as being the problem, it was the combination with the new NVIDIA drivers that was truly at fault.
Some additional notes
- I am running the latest Intel drivers (Wireless.v15.3.1)
- my system has a built-in Realtek audio device. I found the best version of the HDAC drivers is R2.42 --> the latest version (R2.70) would cause a hang on install.
Hope this helps someone cause it wasted my whole day 
Cheers!