Trouble connecting to Exchange 2010 autodiscover

I have been working on this for a week now.  Over a week ago i isntalled an Exchange 2010 mail server into our domain.  We had a 2003 DC, installed a 2008R2 DC (but all rolls still live on the 2003 server), i migrated everything from the Exchange 2003 server to the Excahnge 2010 server with abstolutely no issuse.  I decomissioned the old Exchange 2003 mail server.  Everything works fine EXCEPT, when internal clients connect using OUtlook (no matter what version) it continually promtps for user name and password.  They can send and receive emial but keep getting prompted for user name and password.  When i try to connect to https:/mail.domain.com/autodiscover/autodiscover.xml i cannot and it tells me could not authenticate.  This only happens on Windows 7 clients, it appears that all Windows XP clients work fine.  When i run the Outlook test autodiscover it comes back with a 401 failure message.

All of a sudden the middle of this week everything started working fine and all cleints could get to Outlook without the user name and password prompts, could get to the autodiscover.xml fine.  I rebooted all servers last night and now things are back to the way they were not authenticating.

My critical issue is the i have @ 50 outside users that connect via RPC and without the autodiscover working they cannot connect.