Unfortunately no one can be told what fun_plug is - you have to see it for yourself.
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I am running a DNS-323 with 2 x 1Tb Western Digital Green HD (2 separate drives; no RAID or JBOD).
I just updated the firmware to 1.06...but initially I wasn't able to delete the files in the BT directories (complete, incomplete etc...).
I figured out the fix:
1) Install firmware 1.06 and restart
2) Install Easy Search Utility v4.4.0.0
3) Run Easy Search Utility
4) Click on Bittorrent Button (wait for install and restart)
Now the the Bittorrent download files can be deleted!
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