I have flashed a new rom and changed my PRL. If your flashing a Stock ROM it is more likely to happen because some of them have PRL's in the RUU.
Get your PRL from
HERE.
Sprint Dial ##prl#...
Enter your MSL number (PassWord)......(
MSL Generator.zip)
Hold on update PRL....
Browse to your SD Card where you have the new PRL....
Select and it will reboot...