Thanks for your suggestion, however this does not apply. The entire site is created from scratch using a complete newly installed DW5 AND HTML editor 3.0.1. So there is no old tables like you suggest.
The HTML-editor loads just fine on my form pages, however the filebrowser won't load with the error message above, and there are no tables created.
I HAVE double checked and the database connection is correctly set up.
Any other thoughts? Thank you for helping!!!