I've done the Jelly Bean update yesterday night through Kies while my phone was connected to my computer.
Update was perfect until I tried the software update app to check if there was anything left to install.
At this moment, I had a message telling me that my phone was modified and updates will not work (I don't remember the exact message).
If I go to Settings, About device, Status... Device Status is "modified".
Again, I don't have anything on my phone to root my device.
So what I tried next... removing my microsd card (64GB Sandisk microSDXC) and reboot my phone. Now, Device status is "Normal".
Put it back again... reboot... and Device status is again "modified".
Format the card... reboot... Device status is Normal.
Put everything back (55GB of music only synched through iSyncr wifi with my Mac)... reboot... Device Status "modified".
So it really looks like that the thing that Samsung uses to detect the "modified" state of the phone is broken in some way because it's detecting my media files (mp3 and m4a) as some sort of modification to the phone... this is completely wrong!!
Am I the only one with this problem?
I will try this week to reduce the amount of music file to see if there is anything that broke the detection system... I will report later if I find anything.
By the way, I found a similar thread with a similar problem... but this thread did not offer any solution and it looks like to be close as I cannot add anything to it.