Hi,
It looks like task is scheduled to ring an alarm. Make sure to turn it off or remove it from the Task Scheduler under Windows Media.
You have to snoop around your tasks, and eventually, you'll see alarm. Right click the "clock" icon and click on remove/Delete.
For more on Task Scheduler refer the following article:
Schedule a task:
http://windows.microsoft.com/en-in/windows/schedule-task#1TC=windows-7
Regards,