if i remeber correct some of these torrent programs use the same ports as mail Clients and avast think it is a mail program
there have been similar cases about this before..... cant remeber how it was solved....
Oh... If you remember, can you tell me right away? Thanks 
I don't know if this applies in this case as you are getting a security certificate error and that could be one of several issues.
One of the issues in some P2P applications that they have configured its communication port to that of a standard email port, 25, 110, 119, 143 (you need to checl your p2p applications settings for any communication port and change it is it is an email port).
Any traffic that comes on those ports would trigger a mail shield redirect so that the content could be scanned. This however, would generally result in an error as the traffic wouldn't be using the expected email protocols expected by the mail shield.
If that was the case I wouldn't expect the security certificate error (your image)
The simple case is you are essentially shooting the messenger, if one of your seeding hosts has an invalid certificate I would be considering not using that IP (Finland, see image) rather than disabling the mail shield or any other shield for that matter.
