Yeah, this is a strange one. I've been trying everything: different jailbreaks (QuickPwn vs PwnageTool), downgrading to 2.0.2, restoring on a different computer.
I've been able to reproduce in every situation. Yesterday I was even having trouble restoring, and when I put stock 2.1 FW on, I was even getting crashes at the lock/emergency call screen (Springboard crashing, UI elements disappearing, system crashing).
Today I restored and used BootNeuter to lock my baseband and un-neuter my bootloader. I haven't had any crashes today, I'll test for a few days.
Next step is convincing Apple to replace the device. That'll be fun.