The spellcheck option in ckeditor is throwing this error when use is attempted. Once the error window appears the screen just freezes unless you go into another menu. I am unsure if the recent update has contributed to this issue.
Wordpress 4.9.4 CiviCRM 4.7.29
Error Message: "WebSpellChecker.net server: The specified customer ID is intended for use with CKEditor only. For more information, please contact us at firstname.lastname@example.org or submit a ticket at webspellchecker.net website."