http://bugs.winehq.org/show_bug.cgi?id=22356
--- Comment #24 from Roderick Colenbrander thunderbird2k@gmail.com 2010-05-13 14:57:37 --- Created an attachment (id=27940) --> (http://bugs.winehq.org/attachment.cgi?id=27940) test patch
Also give this patch a try. I wonder if it would fix the issue you are seeing. It is not a fix but a dirty hack to figure out where the bug is.