problem getting started with metafun -- runaway defininition...

["Mark A. Lilly" <misc@tinorb.com>]

hi all,

i'm trying to get started with metafun, but when i run the command to 
create my metafun.mem
texexec --make --alone en metafun
(from the same directory as metafun.mp resides) i get the following error:

This is MetaPost, Version 0.641 (Web2C 7.3.1) (INIMP)
(/usr/share/texmf/metapost/context/base/metafun.mp
(/usr/share/texmf/metapost/base/plain.mp
Preloading the plain mem file, version 0.63)
<snip a bunch of directory listings>
Runaway definition?
save.showtext;save.beginfig;let.beginfig=begingraphictextfig;save.endfig ETC.
! Forbidden token found while scanning the definition of protectgraphicmacros.
<inserted text>
                 enddef
<to be read again>
                    end
l.49   save end
                      ; let end      = relax ;

I get a nearly identical error when i try to run this basic file:
\starttext
\startuseMPgraphic{dummy}
fill fullcircle scaled 5cm withcolor red ;
\stopuseMPgraphic
\useMPgraphic{dummy}
\stoptext

error:
This is MetaPost, Version 0.641 (Web2C 7.3.1)
Sorry, I can't find the mem file `metafun.mem'; will try `mpost.mem'.
(mpgraph.mp (/usr/share/texmf/metapost/context/mp-tool.mp)
(/usr/share/texmf/metapost/context/mp-spec.mp)
(/usr/share/texmf/metapost/context/base/mp-grph.mp
(/usr/share/texmf/metapost/context/mp-tool.mp)
Runaway definition?
<snip... same as above>


Does anyone have any ideas on this?
thanks,
mark