I had went back to ccleaner 2.18 as 2.19 kept doing something to thunderbird, where everytime thunderbird starts, the message pane would reappear on thunderbird. Deleting localstore.rdf in thunderbird profile worked, but right when running ccleaner 3.19 again, the message pane is back.
Guys, ccleaner is {messing} up applications, which ain't good.
I had my thunderbird profile backed up numerous, if it wasn't I'd be one pisssed off person.
Better fix this, and I bet real soon, this thread is gonna pile up with the same problem. Give it a week.
Stop ccleaner from corrupting localstore.rdf in thunderbird.
I can't be as thorough as Drifus, but I can confirm the problem. I installed CCleaner 3.19.1721 (64-bit) tonight, ran it, opened Thunderbird, and saw a message pane had been added to my layout. I also noticed the quick filter bar had been added. I removed the quick filter bar and message pane, closed Thunderbird, ran CCleaner, opened Thunderbird, and saw the message pane and quick filter bar had been added again. I removed them and closed Thunderbird.
I looked at CCleaner's Thunderbird settings and guessed that session might be the culprit. I unchecked session, ran CCleaner, opened Thunderbird, and the message pane and the quick filter bar were not there, which was the way I had set them. Session appears to be what adds the message pane and quick filter bar.
CCleaner Thunderbird options checked when problem occurs