Sorry I forgot to write it and thanks for the quick response!
It´s Dreamweaver CS4
This Problem with the Javascript errors happened with different extensions from the first time on I installed them. So I´d followed once your intructions for troubleshooting but after the error on Cookies Toolkit still appeared. But for the most bugs it did help.
Yesterday I thought I take care of this Problem now and realized that there´s an update on CookiesToolkit to Version 3.1.3 and so I installed it, hoping to get relifed from this error – but still no luck :-(