[Zope] How to let user get login page without HTTP "redirect" with exUserFolder?

Hi, I am quite new to zope. I just installed exUserFolder and tried it. It works excellent. However, I noticed that before the login page appear, the "stack trackback" and some error message page glimpsed on the browser. I then find that the browser is redirected to the login form with HTTP redirect. I don't want to let user notice the redirect, if the connection is slow, user would be confused by the error message. I hope to redirect to the login page at the "server side". How can I do this? Thanks very much! Ren Bing