Ok I had to check it several times but I was able to reproduce. This is vBET bug. If user has set his default language other than forum language, then vBET adds additional option for editor. Here we forgot to check this condition and we always add some Java Script even if option was not added - this is the cause of the issue.
For quick fix please:
1. Go to Admin CP -> Plugins & Products -> Plugin Manager
2. Find plugin named: Handle default language for CMS article comments
3. Edit it - find:
Code:
$view->comment_block = str_replace('if (comment_postid > 0)', 'if (document.getElementById(\'vbet_addbbcodes\').checked) {
4. Replace by:
Code:
$view->comment_block = str_replace('if (comment_postid > 0)', 'if (document.getElementById(\'vbet_addbbcodes\') && document.getElementById(\'vbet_addbbcodes\').checked) {
This is tested and will be included in next release. Please confirm that it help.