trial version of Restorator alters files to what extent?

When you save a file you've edited in the trial version of Restorator, you get a message that says the file will be additonally altered:

A top-level menu item is added.
and
Dialogs will have a string added.

My question is, can this affect the edited file to the point where it doesn't work, if the program is finicky?

I'm asking because I tried to use it to change a couple of png files in itunes.dll. The changes were successful, but when I substituted the file for the original file, iTunes wouldn't open.

I use ResHacker for bitmaps without a problem, but for some reason it doesn't work with PNGs. It's a pain to have to buy such an expensive program just to edit those, but I might consider it. But I need to know why this file isn't working.

Thanks,
Ellen

Having tried again with ResTuner, successfully replacing the PNG files, and gotten the same response from iTunes, I've concluded this has to do with iTunes, not Restorator, and I'm starting a new thread.