Hi Patchou! I'm here again, with the same old problem:
The thing is, that I updated my old Version 3.01.94, to 3.20.100 Version, because you said in the Changelog section "The encryption password problem has finally been fixed!" and it's not true. I copied the five files I couldn't unencrypt before into the archive file in Messenger Plus, hopeing that when I encrypted the new files it would replace the old encryption key with a new key. Unfortunately, the new files were encrypted, but the old files remained with the old encryption key. When I tried to unencrypt the new files, those files could also not be unencrypted. Fortunately, I backed up my files before I encrypted them.
Obviously, the patch in version 3.20.100 does not work. My only hope is that you might find a way to unencrypt the old files, because they're very important to me. "I hereby pledge to never use the encryption option in Messenger Plus until this particular bug is fixed. So help me God."
Other than this problem, I enjoy using Messenger Plus. With that said... please respond to this post A.S.A.P. Thank You!

The bugfix does work. I think you may be slightly confused as to why you can't decrypt though. The reason you can't decrypt the old logs is because they are corrupted irretrievably. Though I'll admit, not being able to decrypt newer logs is also a problem.

Anyway, to make sure you have all the latest bugfixes, get 3.25 from the homepage.