Pre-requisites for posting in this thread:
-You're on the latest stable firmware for the X3 or X5. (3.0 and 2.0 respectively as of June 2014)
-You've had your player hang up on you either during library updates or music playback.
-Said hang-ups have occurred more than once to an extent that it is affecting your enjoyment of the player and you're beginning to see a pattern to the hang-ups that you can report.
When reporting the hangups, please include as much information as you can, including for example:
-Your best understanding of when such lockups may be triggered (e.g. a particular song, album, player setting, etc.)
-What you have done that seems to help avoid such lockups
-What you have needed to do to recover from said lockups (from the usual reset pin and/or hold power button for 15s to more unconventional recoveries, such as pulling / reconnecting headphones, to extreme measures such as having the battery run flat)
-Brand of SD card used, where it was bought, how it is formatted (FAT32 or otherwise, formatted in-player using latest firmware revision or otherwise)
-Any other info you deem relevant and consider helpful for troubleshooting
Your report of your problem here will help us improve the X3 and X5 firmware to accommodate all use cases to prevent lock-ups in the future!