I'm sorry I can't precise more (I'm not in front of my computer), but if you have the script, in line 21 it says
Use_class_id = false # Advance characters based on the class ID
I think that if you put
Use_class_id = true # Advance characters based on the class ID
from this line
# Format = {Actor.id (or class_id) => Amount to raise}
Actor_HP = {1 => 5, 2 => 5}
the red numbers changed to be the class_id of the database.
Well, when I change Use_class_id = false to true, it's when I get that error.
I think there's no conflict whit other scripts I use, because it also happens in a new project with default scripts.
If you need more precision, I will make a more precise post when I get home (in 2 days)
Thanks again,
Agju