It's nice know that i'm not the only one who has suffered this Imprisonment CTD. He HeI have also been having the imprisonment ctd for years, so you are not alone.
That was a fascinating converstation with Hoppy. As you both described the spell is messed up, and I have encountered it a lot with high level mages and liches throughout the game. Like Hoppy said, it is something with refinements that I couldn't fix. (Also had problems with petrification, in the end just didn't install that)
What I tried to narrow down the options was:
1)Don't install Pro5Tweak - this didn't help (it would drop the items if the spell worked)
2)Don't install BigTweaks - this allows you to get imprisoned (and ends game if its the pc)
3)Put the original imprisonment spell SPWI910.SPL back into override folder after the install finished (along with the Pro5Tweak)
That seems to work for now. Sometimes the items that protect against that spell type (abjuration?) don't work, but enrage/beserk do work. In the end have Korgan/Minsc attack, or if you have an item that beserks you try that. If they blast you with imprisonment and you don't expect it, then its time to reload...
Well i don't know about other items but i have always used Geirthan's Plate from Deidre and it haven't ever let me down so far. My CHARNAME is always fighter (no kits).
Usually i can't use these berserker NPCs Korgan or Minsc because they aren't that long in my party (i boot them after their quests are over) it's my "Super NPC Switching" playstyle. I don't know about these berserker items i haven't ever try them. Maybe i try sometimes.
I don't remember that i ever had petrification CTD problem. Maybe it's that i have always used some kind of protection from petrification. I don't know i might test this later tonight.
