Recent nightly builds are created with the option --disable-shared active. However, this makes it impossible to have Enigmail running. The core of Enigmail is a shared libary which cannot be loaded with this option enabled. Recent nightly builds just crash with a segfault when Enigmail is accessed.
I don't think this is the cause of the problem you are seeing Patrick. We've always released static builds on (i.e. --disable-shared) on all platforms since Thunderbird 0.7 or so.
Right, I'm sorry.