I have bought Nexus S due to to the Prime release and therefore the S got a lot cheaper.
I have rooted the phone, so far so good.. ??
Now i have trouble upgrading from 2.3.4 to 2.3.6 both OTA and manually.
Have tried both twice and no success.
Do i have to unroot the phone and how to do that?

Ice Cream Sandwich is coming soon, will i have trouble again?
How to upgrade my rooted phone to that? When? (Live in Denmark, Europe).