Yes, I had this problem also. You can perform a hard reset, that will solve it but then you loose all your data and it is a pain! So I spent all day trying to find out how to fix it without doing a hard reset, and here are the results:

1. Open the Clock & Alarms app, and click on the Alarms tab. Make sure everything is unticked and unselected.

2. Install and launch MemMaid (http://www.dinarsoft.com/ - Note: MemMaid is shareware that expires after something like 30 days, or you might use another app which allows you to edit the notifications queue), and then press the Jump To softkey and click on the the Notification Queue option.

3. Press the Find Duplicate button, and make sure you say yes to deleting all duplicates.

4. Now you have to scroll through the list slowly, you must find all the ones which have this text in them and check the tickbox: \Windows\clock.exe.

5. Now you have located the rogue alarm notifications and ticked them, press the Delete button and confirm in the next step. Make sure you have NOT ticked/selected any other notifications except the clock.exe ones before you do this step, otherwise it can easily make your phone stop working!

6. Soft reset your device. When it has finished booting, you should notice that it doesn't vibrate madly with alarms for 20 minutes like it used to do before, and you should have a flashing green LED on the right instead of orange

7. Stop using the built-in clock & alarms app if you don't want this to happen again - it is too buggy! Find a replacement alarm app, there are loads of free ones out there!