- Does this occur in your 45.6.0 version only, i.e. there was no issue in previous versions? - Do you use any add-ons, and if so, can you reproduce the issue when in you start Thunderbird in Safe Mode / choose Restart with Add-ons Disabled? If not, restart Thunderbird back to normal afterwards, disable all add-ons and re-enable them one by one to find the offender, and make sure they are up-to-date anyway. - There is also an old but unreproducible bug for this issue, which could also indicate an add-on is responsible. As you see there, you can use the Format > Discontinue Text Styles menu item or use Ctrl+Shift+Y. Does that stop it?

Hello Tonnes, This is embarrassing. Trying the discontinue text styles did not help. I tried to reboot in safe mode but the F8 didn't work and I got back in to full windows 7. But since the reboot I have not been able to reproduce the problem! I don't have any addons that I can find. shockwave flash and VLC web plugin are the only plugins. Maybe something has magically cured the problem. I will keep observing it, of course. It never happened with earlier versions. Is it possible to downgrade to the previous version of Thunderbird, in case the problem comes back? Many thanks for your help. Jack

Hello Jack,

Don’t feel embarrassed. :)

The Safe Mode I mentioned referred to Thunderbird’s Safe Mode, not the one in Windows (see the link above). Sorry for that, but perhaps the reboot just fixed it. In some cases, a reboot can fix issues after a Thunderbird update, so perhaps Thunderbird updated recently? You should be able to see that in the Update History using Options > Advanced > Update > Show Update History. If it didn’t, there could be other issues or "unstabilities" that could be resolved by rebooting Windows, as you may know.

Please do make sure your Flash is up-to-date using the Plugin Check page, unless it is set to update automatically. I am not aware of VLC causing issues in Thunderbird.

You can always downgrade Thunderbird to another version by just uninstalling it and installing another version - all data and settings should be retained. Do make sure to download Thunderbird from here. Browse the folder structure for any win32 version in your case - 64-bit versions are not supported (yet, but should be soon).

Please feel free to mark one of the posts as a solution, or wait a bit until you are sure the issue doesn’t return.

Hello Tonnes, Sadly my success with the reboot was short-lived! It came back again. I tried the solutions suggested but was not able to get it corrected. So I downloaded 4.5.1 from the link you gave me and uninstalled/reinstalled. So far it is working fine! Many thanks. Jack