I am having the same issue (and never been with sprint). I started a thread here:
http://forum.ppcgeeks.com/showthread.php?t=84993
i have talked with tier 2 and tier 3; performed several hard resets; re-programmed (*228 option 1); updated towers and firmware (*228 option 2).
usually, some combination results in an apparent solution, only to revert by to 1x.
John