"Fatal error" when attempting to Copy+Paste an image

Which type of image: bitmap or SVG used as button? I presume you don't mean the old type of image button. And you were copy/paste within the same project?

Did that image used as button have an attached Advanced action? If yes, can you post a screenshot of the Preview of that action?

You always need to be very careful when deleting advanced actions, even though you think they had no usage. It is possible that they are still linked to some item in the project.

Firstly, you need to find out whether this issue is across all projects or just the one you are working on.

Can you create a new blank project and recreate the issue there by copy/pasting an image button that is totally unrelated to your current project?  I.e. Not using the same image or button settings.   If only one project is affect and not all projects, then your Captivate installation would appear to be OK and the issue is isolated to your project or the components you are trying to copy/paste.

What happens if you remove the button settings to make it nothing more than an image again?  Do you get the same error? It could be that in the process of removing unused Advanced Actions you have introduced a conflict because one or more of those redundant actions were actually connected to the image.  Removing the actions and/or Use as Button setting (so that the image is no longer a button) might remove the conflict.

If removing the button setting or actions makes no difference, then try a different image to see if the image file is corrupted.  If the issue seems isolated to a specific image or object, delete it and recreate again with a fresh image.  If it seems to be related to a specific slide in the project, delete that slide and recreate from scratch.

If you still get the error on that particular project but not on other new projects, it is possible that your project CPTX has become corrupted and might need to be recreated.