outlook 2007 & 2010 password promt

I have just migrated from exchange 2007 to 2010, and now, on Every windows XP computer, the PCs are prompting for a username and password.  This is happening to both outlook 2007 and 2010.  I made sure that the required SP and CU have been installed and it's still happening. 

I have performed the following, with no success:
1. reset the user's password in AD
2. deleted the .ost file

3. deleted the outlook profile4. ensured that it has the latest SP, and CU updates to be compatible with exchange 2013

I have tried the below articles, but none have worked. 
http://support.microsoft.com/kb/2264398

http://support.microsoft.com/kb/319206

http://www.interworks.com/blogs/esprague/2013/07/15/microsoft-outlook-exchange-unavailable-outlook-must-be-online-or-connected

Dan