You will need to remove the Microsoft Hotfix program (add/remove programs) and also remove all your e-mail accounts and start from the beginning. After you remove the Hotfix and the email accounts do a soft reset. Once your Touch Pro is back up and running make sure the Active Sync is not running.
#1: Put all the email accounts onto your Touch Pro that you plan on using, fully run the setup for each account.
#2: Install the Microsoft Hotfix and soft reboot.
Ever since I did that a few months ago I have not once seen the user ID/Password issue happen to me again.
I hope this helps you out, please leave me a thanks if it does
...best wishes.