Tutorial: Editing Compressed Graphics

The utility can be a bit iffy, I have enough trouble trying to simply open it these days with windows 10. I need to work with it via the Task Manager.
I'm not sure what the crash issue is about if you're following the correct steps, your settings there are okay.
Firstly you just load your ROM from the 'Open ROM' tab, then next thing you'd wanna do is input the Start and End like it appears you have, then simply hit the 'Copy to Buffer' to have the hex show up in the 2nd Image window, assuming you inputted the correct offsets it should show up there without crashing.

That error there you showed looks like you are trying to decompress the image? And it says 'path name is not legal'... did you choose a file name for it there on the 'Filename' tab first before hitting decompress? You need to first name what the file will be and where it will go, at least that's what my first guess would be with that error.