Oh I see you have Sprint now. Do the following:
1) Go to
here and download Sprint PRL 60613.
2) Put the PRL file onto the \My Documents folder.
3) Dial ##775# (##PRL#) and enter the MSL (unlock code).
4) Tap the Update PRL and push Menu->Edit. Push Browse then push the OK button.
5) Push OK and push Menu->OK. Then just soft reset.
That should help.