Try start Thunderbird in Safe Mode:

• Safe Mode

Also, you can try repair the Inbox, click with right button on the Inbox folder then click on Properties and click on Repair Folder

I'm afraid I have tried both of those (safe mode and repair folder - thanks for trying.

Try restarting with Windows safe mode with networking.

see here http://thunderbirdtweaks.blogspot.com.au/2014/02/basic-troubleshooting-for-thunderbird.html

I have tried starting TB in safe mode - intermittent response. It isd not the downloading of messages - I can click on the email which has an attachemtn and see the message. Then the next time I do it it all locks up - the program will close down but leaves its process hanging so I have to end it in Task Manager. I have put the Error Console into it as a Addon and these messages appear:= 1. Could not read chrome manifest 'file:///C:/Program%20Files%20(x86)/Mozilla%20Thunderbird/chrome.manifest'. (thats cos it aint there and what has chrome to do with TB? 2. While creating services from category 'profile-after-change', could not create service for entry 'Disk Space Watcher Service', contract ID '@mozilla.org/toolkit/disk-space-watcher;1' {if this is looking for space to save messages/attachments to temporarily this could be the problem) 3. 2014-03-01 15:20:40 gloda.datastore ERROR got error in _asyncTrackerListener.handleError(): 19: constraint failed

Windows safe mode... I said nothing of Thunderbird safe mode, although my blog post mentions it as one of the steps.

Hi Matt - sorry - tried both - in Windows Safe Mode, windows installer tries to get in to the act when you click on the email "preparing to install" and just sits there. With or without the addons it still opens the email abouit one time in three, locking up totally (apart from being able to click on the X to shut it down and then you still have to go into Task Manager to get rid of the process (which seems stuck on 13% CPU)

Given that the windows installer wants to play, I am thinking there are some issues with DLL files. While it rarely helps, perhaps this is one of those occasions. Download the current version of Thunderbird and install it over what you already have as a repair. Any better?

try explicitly disabling email scanning in your anti virus program. It might even be worth excluding your Thunderbird profile folder from on access scanning, just to test the waters.

You might also try disabling the global indexer Tools menu (Alt + T) > options > advanced > general This can cause problems if the index is corrupt. again just test the waters.

Hi Matt - last try for today - installed latest version - disabled virus scanning; disbled global indexer tool - no change. What looks like Windows installer flickers in and out when loading and when I click on the email but never stays long enough to tell me what the heck it wants. Emails still stick at "Loading Message" if they have an attachment and Task Manager has to be used to remove the process left. Got to leave it for now or the wife will kill me - friends to dinner!! Thanks for trying