Originally Posted by wildalan
if I try to check for software update I get this
so rooting is the reason?
I'm not sure why you are surprised? it's well known that Samsung doesn't sanction rooting. If they did, we wouldn't need exploits like Towel root to root our phones.
When you check for an update, the update utility has a quick look at your system to see if the system files are as expected and discovers that key files have changed (because you rooted). And insists that you go back to stock before the update proceeds. If you think about it a moment, the message you received makes perfect sense.
It's questionable if you should update at all if you have a rooted system. If you do, then you ought to be doing it manually in a controlled manner. Which is to say that you don't let the system check for updates itself. Instead download the new firmware, then use something like Mobile Odin Pro to write the .tar file, choosing everroot, inject superuser and wipe cache.