New beta -- beg for rescue

[AlterEgo Qasars <quasar@econ.muni.cz>]

Good evening!

I've uploaded and installed new beta (from 
http://context.ct.utwente.nl/context/cont-tmf.zip) to be able to implement 
hints Mr. Hagen gave me.

And now I can't compile my document. The truble is in heads. I have 
something like this:

\setuphead[chapter]
	[style={\ss\bfd\setupinterlinespace[line=40pt]\red},
	command=\MyChapter]
\def\MyChapter#1#2{%
	\framed[width=7cm, background=color,
	backgroundcolor=black]{#1. #2}}

\starttext
\chapter{bum}
adfh
\chapter{bac}
asdf
\stoptext

With my former (approximately one year old ConTeXt) it worked. Now I got 
such error message:

! Missing } inserted.
<inserted text>
                }
<to be read again>
                   \endgroup
<argument> ...tionnumber }}}\fi \dostopattributes
                                                  \dostopattributes
\MyChapter ...und=color, backgroundcolor=black]{#1
                                                  . #2}
\doplaatskopnummertekst ...tes \dostopattributes }
                                                  }\fi \endheadplacement 
{#1...

\dodododosomekop ...mmer ]{\finalsectionnumber }}}
                                                  \writesection 
{#1}{#3}{#4}...
l.9 \chapter{bum}

What's wrong? How can I improve it?

Many thanks. (Well, I'm getting desperate since the deadline for the 
typesetting is nearly over. Please help.)

Michal Kvasnicka