I suggest you compare the accounts information on both devices from the troubleshooting information. Please also post the Mail and News Accounts information from both profiles here To find the Troubleshooting information: * Open Help (or click on three-line-icon and select Help) * Choose Troubleshooting Information * Use the button Copy to clipboard to select all. Do not check box "Include account names"! * Paste this in your post. Please also add the result of these troubleshooting steps to your post *Does Thunderbird work in TB Safe mode (see [http://mzl.la/1k5DWjq Thunderbird Safe Mode])? *Do you use anti-virus and firewall software? What is the version? *Who is the email provider? *Who is the internet provider? *What is the exact error message? *What steps did you take right before this happened? Please post back with this information and any other questions you might have.