Actually, my Nexus S gets really weird after upgrading to JRO03E, before upgrade, my Nexus was using stock ICS and stock recovery...locked and unrooted.
It refuses to connect to my home Wi-Fi due to "poor reception", even I place my Nexus next to the Wi-Fi router.
Besides, my app drawer is messed-up like jojost.
I simply did a factory reset and every thing is working fine now.
I suspect some apps incompatible with JB 4.1.1 messed up the whole system...