Unlock Works Fine Until iTunes Sync

[jonlarge]

I am having a very unusual problem with my iPhone, one that I cannot find any other posts about.

I unlocked/jailbroke my 2G iPhone into 2.2.1 using QuickPwn for Windows. Everything worked fine.

I then went to sync it with iTunes on my MacBook (I cannot run QuickPwn on my Mac because of the DFU mode update in Leopard). I sync it and everything appears fine. But almost immediately after the sync is finished and I disconnect my phone, I lose service. It displays "searching" and then eventually says "No Service."

I have tried taking my SIM card out and replacing it (I even got a new SIM card from my carrier. I also tired resetting the Network settings and rebooting the phone. No luck with anything.

Do you guys have any ideas?

[iamnintendork]

Is it activated through iTunes?

[jonlarge]

No. I don't have AT&T, so I use QuickPwn to activate it.

[bhz1]

If you update Leopard to 10.5.7 it fixes DFU issues.