Does your Thunderbird load some of your messages, only to get stuck with the "initializing..." message at the bottom right corner of the screen?
I was getting this error, and it would persist after killing and restarting thunderbird. I have multiple accounts, all of which use IMAP. Some of the accounts would synchronize, but then one would get stuck.
On one of the German OpenSuse forums, I found a hint which solved my problem.
Open the Thunderbird menu (where all the options are found), and select "Add Ons", and then "Extensions" on the left panel. If you see "TrackerBird" listed, click the button labeled disable, and restart Thunderbird.
Let me know if this fixed your issue! Hopefully someone sees this information, and does something more useful with in than I have.