If you unlocked your iPhone 3G or 3GS using Ultrasn0w and are having random problems with it, try unlocking it again by running the latest Ultrasn0w version 0.9. According to the iPhone Dev-Team, this new version includes the following features:
Works on both 3G and 3GS
Works on hacktivated devices
Works regardless of how you jailbroke your device
Doesn’t patch any mach-o binary whatsoever. (Doesn’t require a separate patch as each new firmware comes out).
Doesn’t install any additional daemon
Has no race conditions, no popups about “Missing SIM”, no network issues
Is almost 7000 times smaller than its nearest competition :)
Is available now via Cydia. Source repo is http://repo666.ultrasn0w.com (that last “0” in ultrasn0w is a zero!)
The Dev-Team is grateful to GeoHot who gave them the source code for his Purplesn0w tool, as they were able to tweak Ultrasn0w to fix several random issues, and at the same time make it even better than Purplesn0w itself.