[Mutiny32]

Sounds like an internal hardware issue. Your internal ROM image storage may be bad. NAND flash isn't perfect. Just to be sure, take out the microSD card, do a hard reset under a full charge.

Sprint should still replace it if you have TEP, as that is tied to the phone number, not the phone. or at the very least, HTC will replace it under the 1 yr manfacturer warranty.

BE SURE TO REFLASH TO THE STOCK SPRINT ROM AND RE-LOCK IT BEFORE DOING ANY WARRANTY WORK OR ELSE YOU WILL BE S.O.L.