Quoted from aspfaq.com:
"If you are using IE 5.5 or IE 6.0, and your local server name has an underscore or other non-alphanumeric character (other than a dash) in the name, then cookies will not work correctly. One workaround is to access the machine by IP address; others include renaming the server or at least adding an entry to the clients' hosts files, or alter your local DNS/WINS, or add a new host header to the web server, with a more friendly name."
For other possible causes of this problem, see
Consultant for some info on using Text Editor as a HTML editor.