Help Can't get back on network after 2G only mode

[spudgunner]

I bought a Nexus S a few days ago, since then I've rooted and unlocked it. I first tried Cyanogenmod 7 (stable) and noticed that I couldn't reconnect to the network (3g or otherwise) after switching to 2g only mode and trying to go back. Thinking it was a problem with Cyanogenmod 7 (as there have been similar problems during the build cycle) I found the full base version of Android 2.3.3 and used it to go back to the stock operating system. The problem still persists. I can get around it by using the Clockworkmod Recovery to completely wipe the phone and flash it again.

Anyone have suggestions?