This procedure works for me:
1. Stop the P2P application
2. Delete the P2P application
3. Delete the most recently added torrent(s) when P2P stopped working...any torrents which were d/l fine before P2P messed up can be left in "incomplete" (they will still be there after you delete and reinstall P2P)
4. Reinstall the P2P application
5. P2P should be good to go again
5. Restart the torrents you still have in incomplete...all is not lost, the P2P program will continue where it has left off if you add the same .torrent file so you don't have to start d/ling from the beginning
And last but most importantly:
6. Wait for fix to P2P application!

(I can't complain too much though since I bought the DNS-321 not knowing there was a P2P application...I'm glad D-Link added it!)