Windows 7 - Power Plan not functioning

Recently got Windows 7 machine and gradually getting it to the way I want it.
However the balanced power plan which was fine at the start has ceased to work. All options appear available but selecting a change and saving produces no change to the actual performance of the PC - it simply keeps going.

Is this a known issue with 7? Any advice will be appreciated.

The factory preinstall may have added to the Power Plan to cause it to malfunction. All of the factory bloatware and useless utilities burden Windows 7 from being the featherlight, instantaneous OS it is meant to be.

Try running SFC /SCANNOW Command - System File Checker to see if it needs repairing.

If that fails, consider a Repair Install by finding an installer for your version to copy, or to unlock all versions. If you have SP1 you'll need to slipstream SP1 into the ISO using this method: Slipstream Windows 7 SP1 into a Installation DVD or ISO File

I have good results running Repair Install on even the most bloated factory preinstalls, however you might want to consider if you find an installer getting the best perfromance out of Windows 7 by clean reintsalling without the factory bloatware and useless factory Utilities which have better versions built into Windows 7: re-install windows 7

Thanks Gregrocker for the prompt reply and useful links.
The "sfc /verifyonly" method revealed no integrity issues, so looks like maybe a System Restore or two in the first instance.

Thanks again for the advice.

Good idea. Try to choose a date before the problem began. If System Restore balks or has problems from Windows 7, run it from System Recovery Options so it isn't dependent upon the OS to run itself.