I experienced my first error after jailbreak my new ipad 3. I got screen stuck after I installed mountainlioncenter and restart springboard. The springboard got stuck for few minutes without response. My new iPad 3 is still running and detectable by iTunes but not able to restart the springboard. At the end, I decided to do hard reset. Hard reset is force shutdown and restart your IOS devices without saving any data at that moment. You will not lost any apps or data that already saved before hard reset.