I updated Galaxy2 (not rooted.....yet) via Kies from 2.3.5 to 4.1.2 JBean. No camera, alarm, music player, or gallery and had the annoying process media error message almost constantly.
Tried removing SD card, disabling account syncs and cleared every cache there is with no change.
Disabled DRM protected content and disable Media storage apps, using settings> application manager>all.
This basically stops any access to any media (music, ring tones, sd card ,photos, etc).
So I reluctantly did a factory reset not expecting it to work...but it did
Worth a try.