AI Copying Error

[vonfrank]

I've been successful in copying AI's from one character to another on many occasions. I use Lord Silva's AI copying technique and I have never had problems before.

Yesterday using the same techniques I copied the AI of ID: 4 to ID's 60-66 when I ran into a problem. The new ID's now properly use their new AI with no problems, but now characters with ID's 1 and 2 (there might be more as well) crash the game when they are put as computer controlled.

I really don't know exactly why this happened, but I do have a theory.

I noticed this while modifying the exe in ollydebug.

I replaced the line that determines the start of the AI for ID: 4

Code:

004041F1   . 83B8 F4060000 >CMP DWORD PTR DS:[EAX+6F4],4

with this

Code:

004041F1   . E9 94230400    JMP lf2.0044658A

just like Lord Silva's guide describes.

For some reason, once I do that, two extra lines of code come out of nowhere and appear right after the changed line, making it all look like this:

Code:

004041F1   . E9 94230400    JMP lf2_erro.0044658A
004041F6     90             NOP
004041F7     90             NOP
004041F8   . 0F85 63010000  JNZ lf2_erro.00404361
004041FE   > 81B9 08030000 >CMP DWORD PTR DS:[ECX+308],168

What does NOP mean? could that be causing an error leading to ID's 1 and 2 not being 'read'?

If anyone needs further clarification, I can try to add more info.
Any help would be greatly appreciated.