Originally Posted by Nimdock

Ok, before you do a hard reset you need to back up any and all information that is important to you (settings, contacts, calendar, etc)... Whatever is not on the SD card will be wiped! The SD is safe though.

To perform the hard reset go to Start - Settings - System - Clear Storage. Don't select NAND.

That's it, the phone will do its thing as if the ROM was just installed.