HTC EVO 4G

I've had my Evo for less than a week, love the phone BUT it has crashed twice. The first time Sprint said "send it back, restocking fee of $35, and we don't know when you will get a replacement." Fortunately it eventually started.

Now it has done it again, it hangs (start screens just loop) after replacing the battery and powering it up, any suggestions on how to stop it from hanging when rebooting it?