try Windows key +R Type thunderbird -offline Press enter.

This should start Thunderbird in offline mode, hence no accounts are checked. Does it help at all with getting the program started and stable?

Matt, Thanks for the suggestion, but it still closes within a couple of seconds after starting. I am thinking I just need to delete Thunderbird (yes, I have copied my Profile) and do a new install, then set up the accounts again. I should be able to restore the Address book from my Profile, I believe.

Seriously I think there is more here.

Try restarting windows in safe mode with networking and see if it still disappears.

Programs just vanishing without any sort of error message sounds a lit like security software terminating the process. If that is the case reinstalling it will do nothing.

Hi, Matt! Thanks for the thoughts. I tried Safe Mode with the same results, so just ended up totally deleting both program and data and reinstalling, copying my Contact from a backup. Everything working now, but no idea why I had the issue, but thanks for taking the time to h elp.