I have just tried with IE:
Open ADE
Ctrl-Shift-U
Computer Authorization window opens
eBook Vendor shows "Adobe ID", click on Create an Adobe ID
IE opens, enter details, click Create
Message tells me to close browser and continue in ADE
Close browser, Computer Authorization window is still open, no additional information
If I click Authorize, I get a message "Missing login ID or password."
If I click Cancel, then Close, window closes and returns me to ADE; Ctrl-Shift-I still greyed out.