Question : Exchange 2007, Outlook 2007 keeps asking for password

I'm very new to Exchange 2007.  I've got a new network with Outlook 2007 clients.  I added email accounts on each PC w/o any problem, however, after adding the email account and closing Outlook, I get prompted for a username/password whenever I open Outlook.  While Outlook is open, it keeps asking me for the username/password.  All the computers are Windows XP Pro and the server is Windows SBS 2008.  All the computers are joined to the domain.  

A little more background, currently I will not be hosting email with Exchange, just using it to store/share Outlook data.  I'll be using POP accounts for the hosting.  

From reading other posts, I'm guessing this is due to a problem with autodiscover, but I can't seem to isolate it.  When I test autoconfiguration, I get a few errors along the following lines.

Autodiscover to https://sites/Autodiscover/Autodiscover.xml FAILED (0x80040413)

A lot of the advice I've read tells me to make changes to autodiscover in IIS under default websites.  I don't have autodiscover listed there and am not sure if that's something I'm supposed to do manually w/ Exchange 2007 as it certainly did not get installed automatically.

Any advice?

Answer : Exchange 2007, Outlook 2007 keeps asking for password

Exchange 2007 Rollup 9 fixes this problem if you have not already installed it:

http://www.microsoft.com/downloads/details.aspx?FamilyID=55320be2-c65c-48bb-bab8-6335aa7d008c&displaylang=en