I am seeking help for a problem with Thunderbird on my wife’s PC. After years of correct operation, the program started crashing soon after start-up, especially when the address book was opened. Eventually, it would only start in Safe Mode, as otherwise it crashed at start-up. Deleting the Global Database (global-messages-db.sqlite) made no difference. In an attempt to solve the problem, I uninstalled and re-installed Thunderbird. A recent backup of the Thunderbird folder in AppData/Roaming was available, and was replaced after the re-installation. Unfortunately, Thunderbird remained unusable, as the tendency to crash was unchanged. As an experiment, I next replaced the Thunderbird folder in AppData/Roaming by a copy of that folder from my own computer. The result was, that Thunderbird on my wife’s PC functioned correctly, showing my E-mail situation. This suggests, that a file in her Thunderbird folder has become corrupt. Can anybody advise me on how to proceed? One approach I consider, is to start with my own Thunderbird folder in my wife’s PC, and replace the Address book and Mail files by those from her own Thunderbird Folder. Can that be done?