Cannot receive calls if MobileMe is enabled

Hello,

I have an iPhone 1st Gen OS 3.0 unlocked with PwnageTool. The iPhone does not receive that if MobileMe is enabled and the phone is sleeping. I tried different scenarios a couple of times:

1. No Contacts = Receive calls sleeping and awake.
2. Contacts but no MobileMe = Receive calls sleeping and awake.
3. MobileMe Contacts = Cannot receive calls if sleeping.

As soon I delete the MobileMe Account and restart the iPhone, everything works again. I tried adding the MobileMe account directly using Settings, or using iTunes sync, same results.

Anyone else having this issue?