What may be causing this? I've still got 19gig of free space left (according to emplode), AND I've still got about 10gig of files left to upload.

Hm, this probably doesn't have anything to do with your problem, but check for free space from Linux (this assumes you have development image installed):

Connect via serial, quit the player (type q ), then type this cryptic line (the player lacks a certain file necessary for normal 'show free space' command - df - to work):
/sbin/df `echo \`cat /proc/mounts | sed "s/ [^/].*$//" | sed "s/^.* //"\`` 2>/dev/null
(all in one line, enter only at the end - the command will probably wrap to the next physical line).

(In the case you are wondering, this means 'Take file /proc/mounts, delete everything from the blank following the rightmost slash (if any) to the end in each line, also delete beginning of each line up to and including the first blank, feed the result to df command, display normal output, discard error messages'.)

Dragi "Bonzi" Raos
Zagreb, Croatia
Q#5196, MkII#80000376, 18GB green