I'm taking a stab in the dark here. But the question reminds me of something I went through YEARS ago when I ran just a Windows box with Deluge. Ever since then I just copy the configuration pages and make sure to setup Deluge the same way from my last "working" solution.
Here's a few questions:
1) How do you add your torrents, are you using some way of "injecting" them into Deluge, or do you do it by going to the WebUI > Add button > Browsing and uploading a torrent from your computer?
2) Do you have a copy of the TORRENT file copied to your computer?
(My /mnt/traid0 is a RAID0 I have setup that I'm using JUST for torrents)
I want to say I never "copied" the torrents before I had my same sort of issue, and this is what I think I did to fix it. The only downside is the TORRENT file is left there, even after the torrent is deleted from Deluge. Which right now I have 576 TORRENT files in that directory, which is 59MB (which I'm not worried about on 1TB of storage). Sometime if I have to deleted all my currently seeding torrents (after seeding time) I'll go in and wipe this directory.
3) I see in your path that it says 'nfs', does that mean you're storing all your files remotely on a network attached storage or some sort? Got to ask the stupid question, but until you reload the Deluge service... your torrents download fine without erroring?