Did he tell Thunderbird to remember the password?

He could have. He doesn't remember for sure.

There is a box in the ask for password dialog that offers to save the password he has typed. I suggest he uses that. I doubt it will fix the issue, but it might. If the issue continues then there are really only two remaining causes. 1. Defective Anti virus scanning. *Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender. *Restart the operating system in '''[http://en.wikipedia.org/wiki/Safe_mode safe mode with Networking]'''. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: [http://windows.microsoft.com/en-us/windows-8/windows-startup-settings-including-safe-mode Windows 8], [http://windows.microsoft.com/en-us/windows/start-computer-safe-mode#start-computer-safe-mode=windows-7 Windows 7], [http://windows.microsoft.com/en-us/windows/start-computer-safe-mode#start-computer-safe-mode=windows-vista Windows Vista], [http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/boot_failsafe.mspx?mfr=true" Windows XP], [http://support.apple.com/kb/ht1564 OSX] 2. Change in connection setting from the mail provider. We can only help with those if we know what they are and who the mail provider is. Please add the troubleshooting information to your post as well as the results of the following troubleshooting steps: * [https://support.mozilla.org/kb/use-troubleshooting-information-page-fix-firefox#w_accessing-the-troubleshooting-information-page Finding the Troubleshooting information]

I haven't had a chance to try any of your suggestions above Matt, but I wanted to tell you that his provider is Centurylink, who recently did an upgrade to their system, after which his problems started. I worked with their help desk on the original problem and tried putting in the settings they recommended for Thunderbird. It did clear the original trouble but now the password thing has shown up and I'm dealing with it. I hope to get to his house tonite to take another look and see if anything you sent to me will fix the problem. I'll get back with you tomorrow if I get there tonite. Thanks for the info to try.