I've searched the forums and it doesn't seem anyone else has had problems with this, even the earlier Beta version firmware and P2P. Help!!
Not true... I reported issues like these back in beta and was told my copy (of P2P client) was old. I have seen many instances where the P2P client just stops working (terminates with exception) and others where something goes awry and everything seems to be going slow.
I have learned to deal with it though by understanding that ssh, screen, ffp and the filesystem can be used to make sure you can recover when this instability is encountered.
I have ffp installed so I can ssh to the little black box directly. I run screen so when I disconnect my session is still running and I can pop back in later. This is really helpful when I want to know what messages/exceptions were thrown by the p2p client. To manually start / stop the p2p client from ssh you can call /mnt/HD_a2/Nas_Prog/P2P/start.sh or /mnt/HD_a2/Nas_Prog/P2P/stop.sh scripts. When you are running in screen and execute the start script you will see messages output when interacting with the web interface. For example, if you add a torrent via a URL you'll see the P2P client call wget to download the torrent and if you start/stop/delete the torrent you will see those messages as well. This is the best I can do for logging...
Your symtoms sound like what I have seen where you may have left the torrents on for a couple of hours, and the upload/seeding has been going on. I'm not sure if this is the culprit, but I do know from experience that if this p2p client has been running for a while it will eventually fail and slow the box down to where you want to just turn it off-on again.
When I experience this I will run the stop script and notice everything just peps up again. Then comes the manual cleanup. In /mnt/HD_a2/Nas_Prog/P2P/.torrents you'll find potentially three files for each torrent. Their names will be identical except for the extension - .torrent, .fastresume, or .finished. If there is a .finished and the file(s) is found in /mnt/HD_a2/P2P/complete then you can just remove the three torrent files. Once this is cleaned up you can go ahead and run the start script. Everything should run normally again.
One event that I know will cause the p2p client to break is if you've had the webgui open past the expiration limit and you click on the remove completed button. Basically, the P2P page keeps updating becuase it pulls status via AJAX and not a post-back. So when you click the button to remove the completed torrents the page determines that your session expired but the action to remove the torrents is still triggered. But, by then it doesn't know the indexes of the torrents. Rather than handle it gracefully the p2p client throws an exception and dies.
I'd love to see how they implmented the libtorrent code but I never got a response on seeing it. For what it is worth I used to run chroot debian with rtorrent and it worked great, but this method is much easier for the layman (kinda?) and having it plugged in through the webui is a great feature. But, there is still much progress to be made.