Okay, so I think I found a way to replicate the issue (Sort of)
1) Make a new character.
2) Enter the game through character creation.
3) With an immortal character "set" the deleted flag on that level 1 character.
4) Have that character log out normally. (This may also work with having the character delete himself through the login screen, but we don't offer that option)
5) Make a new character with the same name as before.
6) Enter the game through character creation.
*** This players IDNUM is now set to 0, for some reason.
Create a new connection to the mud with your immortal and IDNUM 0 player still logged in, and have them create a new character.
Before finishing character creation, the new character will overtake the IDNUM 0 character without providing a password and the mud will enter an infinite loop.
This, to me, does not make any sense, I am using the stock login/deletion/indexing system that newest TBAMud uses. Perhaps you can duplicate it.
If anyone has any ideas, suggestions, or would like to look for themselves and provide feedback, I will genuinely appreciate it. This has been bugging me for months.