It was the main web-mail extension that won't work. This was due to the Gecko engine changes. Actually there several different Web-mail extension versions that resulted from these changes. We probably end up even another version for the just released TB9 and then another one for the TB10 that is in beta testing already. Webmail wasn't working for TB9 last night nor any it companion extensions.
You should be able to just install the new Hotmail extension in your current setup without; Just don't update the main web-mail extension
