Delete the Dreamweaver Cache file from the users configuration folder:
common_installation_issues.pdf
you can limit the items shown in the format list by editing the webassist/ckeditor/config.js
adding the following line:
config.format_tags = 'p;h4;h3;h2';
will show only Normal, Heading 4, Heading 3 and Heading 2 in the format list.