I cannot reproduce your error.
I can help you to make code changes to make the Comment Form completely disappear after a user edits or posts a comment? That's easy to do, but as soon as they refresh the page it will just reappear
That's actually a decent feature idea, I've seen other comment systems do a thing like that. If you want to do it, here's the steps...
(1)
Open the file /components/com_comment/joscomment/jscripts/client.js in a UTF-8 editor (if you are on Windows 7 and not XP/Vista then you can use built-in Notepad).
(2) Search for this text:
//JOSC_refreshPage('', idsave);
(3)
Replace that line with this text:
document.getElementById('joomlacommentform').innerHTML = '';
...with that change, after the comment is submitted then the comment form will vanish (until the user refreshes the page). You could change the '' after innerHTML to whatever HTML code you want, maybe just some text saying Thank you or something