I installed the update to Thunderbird 7.0 (from 6) on my XP machine and, when run, it opens up 2 windows every time (task manager shows only one copy of the exe running).
Anyone else have this problem?
p.s. I have gone back to version 6 until another update becomes available / the required config setting becomes apparent.
Windows .. or Tabs?
I'm on 7 ... no problems at all yet (even with addons not supposed to even be compatible with T5!)
Try starting it with the actual executable in Program Files ... wherever you have it installed.