I purchased Nexus S in last week of April 2011. Unfortunately it got a water splash. The unlock slide was not repsonding.I called Samsung and told me to send the same to repair center in EL Paso. After three weeks got the phone back with a remark 'BER' which they told me that it is beyond economic repair.
However, on arrival going through the forum I rebooted the phone and the slide started working. I was thrilled and could use the phone. But the phone was needing frequent reboot.

Last two days back it hanged and then on recovery and reboot, its stuck at Welcome screen.

NOW it started on its own but frequently I have to reboot if I have to keep either sound or video streaming working.

Is it an OS issue or something else and how do I reload OSPlease respond.