Processor Idle C2D CPU usage question

[srxshadow]

(New to C2D)
I have a C2D E6400, and it acts strangely from time to time. I see idle cpu usage ranging from 30-50% i tried finding the culprit in my processes, but can't seem to tag it. I noticed that when i restart the system the system goes back to normal and most apps require even less than 5%.

While this 30-50% continuous usage occured i tried several things like logging on and off (single user) setting the system on standby then waking it up, then running for a few seconds CPU stability test, ended up guessing as to which processes could have been abusing it, and practically none of them made a difference as i shut them down. Anti-virus and such also does not indicate any malicious software.

Does anyone know what could cause these random high % numbers on core 1 only??
I am pretty sure i also have all the current drivers for graphics card and mobo.
Please help!
Current system:

Windows XP home edition
E6400 (stock core 2 duo revision B2 )
1GB ram (DDR2 800mhz 6400)
ASUS P5N570 SLI
1x nVidia 7600GT
1x 160gb HD
1x DVD/CD-RW dual layer

 

[Talonz]

Can you take a screenshot of your task manager processes sorted by CPU %?

 

[srxshadow]

In this case it happened resuming the computer from standby mode for about 30 minutes, and it is just the core 1??(left side) that's running, high, core 2 is almost idle.

 

[Talonz]

Try seeing if you can find anything from this utility:

http://www.microsoft.com/technet/sysinternals/ProcessesAndThreads/ProcessExplorer.mspx