It's the current thought that the HD2 doesn't support pre-paid SIMs from any carrier other than T-Mobile for whatever reason...SIM unlocked or not. Try an ATT SIM if you can and see what it does. If the SIMlock.exe program took the unlock code and didn't throw an error, then you are more than likely SIM unlocked.
Verizon Motorola RAZR LTE
Acer Iconia A500
Custom Stock 4.0
Acer STOCK 3.0->Custom Stock 4.0
HTC S620 Excailbur->HTC Wizard->HTC Juno->HTC Herald->HTC Tytn II->HTC HD2/HTC Shift 9500->HTC G2/SGT ATT->LG G2X/SGT ATT->HTC Sensation/SGT ATT->Motorola RAZR LTE/Acer Iconia A500
PARADIGM SHIFT!! Now on Verizon USA.