>I am trying to use the MS Web browser control to access an authenticated site. My program knows the user name and password; how can I pass this to the browser, so that the "enter username and password" box doesn't come up?

That's a good question- I don't know the answer, but my guess is going to be that you can't, because the authentication box is not a IE function, but a windows function.

But your best bet might be

KEYBOARD 'Username'
KEYBOARD '{TAB}'
KEYBOARD 'Password'
KEYBOARD '{ENTER}'