Windows 7: Constant 30% CPU usage in windows 7 when idle

Hello, I'm having a problem where windows utilizes 30% of CPU usage even when Idle.

The problem starts when i open a program like games or any intensive application that requires alot of CPU load. But after closing the program, i noticed in my taskbar that windows generates and continues to use up to 30% of CPU load on other applications for example Dwm.exe (desktop windows management) but if i stop DWN.exe from taskbar, another program or service will replace it and generates the same CPU load, if i stop that another will take its place like svchost or the taskbar.exe itself getting a 25 to 27 cpu load. Its like an ongoing cycle or Loop of CPU usage, its supposed to stop after closing programs.

I already have done steps i thought would clear this problem and these are:
Registry fix
ran Avast Anti-virus
reset BIOS
ran anti malware programs
ran Msconfig and disabled unwanted programs running on the background
ran windows 7 update
updated all my drivers

Summary:
The problem still persist. This problem doesnt occur after boot, everything is fine with my system idle getting 97%. it only starts after i ran a program that utilizes high CPU load but after closing it, the heavy CPU load continues by replacing the closed program with another either dwm.exe,taskmanager.exe,svchost.exe..etc



I hope somebody helps me resolve this problem, i greatly appreciate it. thank you

Never mind i found the problem

Hey buddy.can you tell me how to solve it?

I have exactly the same problem:

Heavy task -> dwm.exe goes to 30-50% CPU -> kill it -> some other task 30-50% CPU -> kill it -> some other task to 30-50% CPU -> ...

Tried everything from antivirus to system cleaners etc - but nothing helps.

Lightwind, could you tell us how to fix it? (PM if this works better.)

Thanks!

My problem was caused by a program, i forgot it's called (some kind of a mobile phone application and USB related programs too) it constantly updates itself that goes on a loop, i guess it's corrupted when it does that. somehow it affects other programs to go on heavy load with it. i deleted it and it's gone. although i heard some people had the same problem but the cause wasn't like mine, some said it was their video card program (due to background updates)...all they did was re-install their OS to solve the issue.