Disable Task Scheduler
In Windows XP by default Task Scheduler does not contain any tasks. If you do not add there your own, like many users, it can be disabled.
In Windows Vista some standard system functions depend on Task Scheduler, including possibility of changing language input. Therefore, if you not assured in your actions, Task Scheduler in Windows Vista is recommended not to disable.
A system reboot is required to apply changes.
Description of Task Scheduler in XP: