Preparing calendar located on server for use fails

[why2jjj]

Hi:

My server location for the Microsoft Exchange calendar address is:

http://AMR\my_login_name@auto

and I get this error when I click next:

An error was encountered preparing the calendar located at http://AMR%5Cjpfreyen@auto/ for use. It will not be available.

Error code: 0x80570015
[Exception... "Component returned failure code: 0x80570015 (NS_ERROR_XPC_CI_RETURNED_FAILURE) [nsIJSCID.createInstance]" nsresult: "0x80570015 (NS_ERROR_XPC_CI_RETURNED_FAILURE)" location: "JS frame :: resource://calendar/modules/calUtils.jsm -> file:///home/jpfreyen/.thunderbird/hc0vfzmr.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/calendar-js/calCalendarManager.js :: cmgr_createCalendar :: line 583" data: no]

This is Thunderbird 5.0 with exchange server .15 and lightning 1.0b4