Oracle Database Express Edition (XE)

i created a new DAD with DBMS_EPG -- works like a charm, sort-of.
after connecting with the DAD, attempting to use the HTMLDB DAD (home page) results in a browser authentication prompt
and after using the logmeoff procedure to deauthenticate, subsequent attempts to access the DAD return a page with

"Bad Request
The HTTP client sent a request that this server could not understand."
(browser window title "400 Bad Request")

1) what's the correct way to deauthenticate a DAD connection with XE without shutting down the browser?
2) does XE support concurrent usage of multiple DAD connections on the same machine?
3) related to 2, should a DBMS_EPG DAD be usable concurrent with the built-in HTMLDB DAD (home page)?

++ mcs