I bought a 1TB Mybook World yesterday. I got it home and immediately used the guides on here to setup SSH, install ushare, screen, disable cron and a load of other services to free up memory. It all worked perfectly.
I then hit a problem where my ext3 /shares/internal filesystem would freeze occasionaly and remount itself in read only mode. I ran fsck (after adding a bigger swap space) but that didn't help.
Eventually I recreated the filesystem and it's been fine ever since.
I thought I'd post this up incase anyone else was having similar problems.
The errors I was getting were : -
Apr 17 12:38:55 NAS user.alert kernel: journal_bmap: journal block not found at offset 3084 on md4
Apr 17 12:38:55 NAS user.err kernel: Aborting journal on device md4.
Apr 17 12:38:55 NAS user.crit kernel: ext3_abort called.
Apr 17 12:38:55 NAS user.crit kernel: EXT3-fs error (device md4): ext3_journal_start_sb: Detected aborted journal
Apr 17 12:38:55 NAS user.crit kernel: Remounting filesystem read-only
Apr 17 12:38:55 NAS user.warn kernel: __journal_remove_journal_head: freeing b_frozen_data
Hope this solution helps somebody else.