I recently added all the PC's in a remote office that was recently acquired to the corporate 2003 domain. The remote office has a dsl connection with a constant VPN connection to corporate. Initially there were no problems but after a week 4 of the 8 users started having issues. The two most obvious issues are that logins for these users take 15 to 30 minutes and the local copy of Outlook will no longer communicate with the Exchange server. The PC can ping the Exchange server by name. These issues follow the users to whatever PC they use in the office. The other 4 users have no problems. They login in less than a minute on any PC in the office.
One of the four users that is having a problem was created after all the problems started on Thursday. Her very first login took around 30 minutes. Her account was created by copying one of the other troubled users.