Ok, something is going really wrong. I found something more.
As I said before, I did a backup of the original portraits I intend to overwrite.
These are the backed up files I still have in my portrait folder:
male_elf_bkp_d_lg.png
male_elf_bkp_d_sm.png
male_human_01_bkp_lg.png
male_human_01_bkp_sm.png
male_human_bkp_n_lg.png
male_human_bkp_n_sm.png
Here is the situation:
1. If I do nothing (keep those files plus the original ones after a re-install) I can run the game and load my saved games.
2. If I delete the backup files and play with the original portraits only, the game crashes after the kickstarter image.
3. If I keep the the backup files but I overwrite the original portraits with the customized version (same name, different image), the game crashes after the kickstarter image.
4. If I delete the backip files plus I overwrite the original portraits with the customized version, the game crashes after the kickstarter image.
Obsidian, please, could you look into that.
I really want to play with my custom portraits as I did before for more than 40 hours.