Another fix for “The process android.process.media has stopped unexpectedly…” that can (also) appear after you upgrade to Lollipop (Android 5.0) from some lower Android version without doing factory reset.
Try to uninstall “DRM Protected Content Storage” app via Settings -> Apps. In my case, this was a left-over of Android 4.3, and android.process.media had some problem with it, resulting in that super
annoying informative dialog…
Btw. if it doesn’t helps, and even nothing else – you’ll have to play with logcat, to discover the problem. “Simply” look for FATAL EXCEPTIONs.