I am running Thunderbird 24.5.0 on a Windows 8.1 operating system (both newly installed). According to Windows / Microsoft Update the only outstanding updates are two optional updates (for Silverlight and Bing Desktop, neither of which do I have or want). Today I prepared a draft e-mail, which was saved in the 'Draft' subfolder of 'Local Folders'. After further review and editing I pressed the 'Send' button to dispatch the e-mail. As expected, the 'Check Spelling' window popped up, and indicated issues with a few words, which were dealt with by variously adding them to the dictionary, correcting them, or ignoring them. When it reached the end of the text however, the spell check continued to pull words out of the hat, presenting over thirty extra "errors". If it is of any help, the words presented seem to be of a "technical" nature, suggesting that the spell check might have got into part of the document or system where it should not be. Examples include "charset", "mso" (many occurrences), "msoNormal", "msoChpDefault", "WordSection", "qformat", "ANSI" and "bidi". I should perhaps add that the original basis of my Thunderbird application, and in particular the structure and contents of the 'Local Folders' hierarchy, were determined by the contents of a profile file created on my old Windows XP system via an import from Outlook Express, that was in turn copied across to my new machine. The draft e-mail that is the subject of this question was however prepared entirely on the new system.