The checking for modification of the files works by opening up files.txt, and SHA1 hashing the contents of each file listed in there cumulatively. If the hash doesn't match the hash stored in the exe, it exits. But theres one problem with this technique... they rely on files.txt to check files.txt too?!!!! Oh dear R*... what happened to your chain of trust?!

To bypass it, all you have to really do is:

1. Make a copy of files.txt.... for example: copy files.txt to files.txt.original
2. Edit files.txt... replace "files.txt" with "files.txt.original"
3. Make a copy of the file you want to mod... say you want to mod weaponinfo.xml, so you would make a copy of it as weaponinfo.xml.original
4. Edit files.txt... replace "weaponinfo.xml" with "weaponinfo.xml.original"


And viola.... no more exiting on startup... but to make your patches really apply you have to use a patched filelist.pak without any files in it.

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So here is a .bat file that will do the above things to all the "protected" files and make backups of them as .magic. Included is a patched filelist.pak as well. After installing this, you can just edit your files normally as before (just don't edit the .magic files!)

To install:

1. Restore backups of ALL your modified files (or if you don't have them, you have to reinstall). It is VERY IMPORTANT that you have the original "protected" files or this won't work!
2. Copy magic.bat to your GTAIV game folder
3. Run magic.bat (Run as Administrator if you're on Vista)
4. Make a backup of pc\data\filelist.pak
5. Overwrite pc\data\filelist.pak with the included filelist.pak.