Yes Heritic is right, and why I've kept any mods to it at a minimum, and a log of what I've done so I can undo it easily.
Yes JSMGE is a friend in this regaurd though I have yet to use it. Since I have only done three mods, two of which were only simple cfg entries for just one command each, the other one just the halo/bubble mod.
And have a back up of all original files.
Always be prepared to undo what you do, before you do.
