Apple Official Guide on iPhone Alaram Problem
Apple iOS4.2 is the permanent solution to this problem.
Users who depend on the iPhone to wake them up should create one-time alarms specifically for Monday morning, We suggest customers set nonrepeating alarms for now and reset after November 7 to resolve the issue spokeswoman Natalie Harrison.
United states user follow these steps to solve this problem
1. Open the Clock application.
2. Click on the Alarm icon at the bottom of the screen.
3. Click the "plus sign" icon in the top right corner.
4. Create an alarm and make sure you have the "repeat" option set to "never." The glitch only occurs with repeat alarms.