Start thunderbird in safe mode - http://support.mozillamessaging.com/en-US/kb/safe-mode

Does problem go away? Please reply to let us know results.

For me the problem the problem goes away in safe mode. I get the error three times (stop script each time) and then everything works fine until I close TB down and come back up to same situ. I have the calendar which does not appear in safe mode.

Most recent error: A script on this page may be busy, or it may have stopped responding. You can stop the script now, or you can continue to see if the script will complete.

Script: chrome://calendar/content/calendar-month-view.xml:918

"Chrome"????

Isn't the calendar part of TB now? Why does safe mode not include the calendar?

Calendar is still an add-on, and as such is disabled in safe mode. What's different in version 38 is Calendar is *packaged*/shipped with Thunderbird

Once you "package/ship" pieces together, that's really a difference without a distinction.

Regardless of what is or is not in safe mode, I still have a problem where my *environment* crashes and it is not usable.

Should I just try to reinstall?

> Once you "package/ship" pieces together, that's really a difference without a distinction.

Clearly there is a distinction which matters :)

Your problem is with a calendar function - and perhaps not the same as the original poster, who has failed to answer. I suggest you post a new support topic for your issue and label it as a calendar issue