Try this: with your phone off...
1. Poke the soft reset hole beside your power button(Poke and Release)
2. Press and hold the Call and Cancel Button together(Do it immediately after Step 1)
3. Do not release Call and Cancel button, the Samsung Omnia Screen Appear
4. The Reset Screen will appear as below
Press Call to Format or End Call to Cancel.
You have to ensure you Prese the Call and Cancel button at the same time when the Samsung Omnia splash screen appears so that it will bring you to the Format screen.
Good luck!