Trying to paste text into HTML and/or save and getting error messages, then CC either freezes or aborts (see attached). Help, please.

Have you tried closing the program and reopen it. I do not mean reopening after it has aborted, but after a regular closing.
Do you have either the split screen or the 'external preview' open when this happens? If you have, close them.

Which Windows version are you running? And which version of the Editor?

What kind of text are you pasting? If it is just normal English language, it should be ok actually, but if you are using some foreign alphabet, it may be the reason.

And, when you installed the HTML Editor, did you install it to the recommended location? If not, uninstall and reinstall.

If you cannot sort it, you'd better contact CC support by going to your support room (click your name top right).

Yes, I tried a clean session restart and am not using either the split screen or external preview. I learned those bugaboos with previous issues with CC. I am running the latest build of Win10 and CC v17.0 865. I am pasting some code from NotePad++ - something I've been able to do countless times in the past with no problems. I learned back in the Windows 95 days to not install applications to custom directories, so - yes CC is in its default install location.

Thanks for the suggestions, tho! : )

I guess you may have tried uninstalling the Editor and reinstalling it too? And if you happen to have a 2nd machine somewhere near, install the Editor and try there.
If all else fails, contact CC support.