Ah I forgot ... for all others:
The BOD-Problem is now solved.
Not really solved ... but I now really know that the Problem was a special email with many many recipients in the To:-Field.
It´s maybe also a problem in avast, but that is not the (only) reason why the bluescreen appears. It´s more a problem in Outpost Firewall and/or in Thunderbird (1.0.6).
I deinstalled avast first and than I reproduced the bluescreen of death in the normal way.
And now I have moved the special email online in a extra directory and now there are no other problems. I have reinstalled avast and it worked fine now!
greetings from germany ...
new avast fan thrash!