I think there might be many more though I can't remember and do not know how many people are facing problems like this.
Not sure about two other cases but for case 2, it seems a terrible practice was made (at least it is what the user told us).
Teleporting an account from Bitcointalk to Altcoinstalks, and using a same password. It breaks an important principle, don't reuse password on different platforms.
I don't know it is a reason or just a fake one, used by the user to fool us but let's say, reuse password is bad practice.
I don't believe admin of Altcoinstalks forum plays bad and do something like this with his forum members but who knows. And let's take this case to make a warning, again
Don't reuse password.
Password must be unique, best if randomly generated, and strong.