Thanks. I will try that, when I find myself desperate enough to boot Windows.

Can't understand why this happens. Isn't this supposed to be an open OS, why can't we fix it without reflashing our devices?

I've taken a look at accounts.db and it seems fine. Studying engineering - stuff like this should not look like magic to me.

Edit: Dusted off my old Macbook and flashed from it (running XP). So far so good. Twitter didn't prompt me after rebooting.
Edit 2: Second reboot went fine, no prompts. This leads me to that accounts.db is not corrupted at all (since it is untouched) after the flash. I suspect something went wrong with the PR1.0>PR1.1 update.