Why does Thunderbird turn on the Message Pane view when I always turn it off?
Question says it all. Sometimes when I restart T'bird, the Message Pane option has been turned on without so much as a by your leave. I never use it, don't like it, and this is profoundly irritating. Yes, I know, it's a little detail, but still profoundly irritating!
Все ответы (3)
Traditionally I blame CCleaner. Do you use it?
See http://thunderbirdtweaks.blogspot.com.au/2012/06/thunderbird-and-ccleaner-or-my-settings.html
I do use it, but on demand, It doesn't run in the system tray, and it must be a good month since I last ran it, so I don't think this is the problem, but thanks for your input.
The fundamental cause will be the same, but it is a matter of identifying the application that is either modifying/removing that file or blocking Thunderbird access to it.
As the most pervasive software that falls into this category is Anti virus software. Create an exception in it for the Thunderbird profile folder and see if the setting sticks. after a couple of starts
Not sure where your profile is?
On the toolbar 
> Help > Troubleshooting information.
Click the Show profile button. The path is shown in the explorer window that opens.