FYI, not so unique after all. I had the exact same problem (not sure if it was related to the 20x upgrade or something else, though). Followed Calcu's advice and flashed the Sprint stock rom found in the first post here:
http://forum.ppcgeeks.com/showthread.php?t=36062 I went ahead and used the Sprint shipped rom, which also reset the radio. I then selected my preferred radio (Sprint Raph), then flashed another rom (Calcu 3.x). I've had no problems since, but now I know how to fix them if I do.
-Ambrose