Did you install the windows critical update notification program?
That will start the scheduler as that is how it is run.

You need to uninstall or disable the critical update notification program to stop the task scheduler.

To disable the critical update notification program you need to click start | run and key msconfig.exe and click OK.
On the dialog box that opens, click on the startup tab.
Locate the entry for CriticalUpdate and remove the check from the check box next to it and click OK or Apply to save any changes.
If prompted to restart, click on No.
Double click on the task scheduler icon in the task bar.
On the window that opens, click on the menu advanced | stop using task scheduler.
You can then close the window.
This should stop the task scheduler from running.