Hi Matthew,

I've been playing with metaobj and luatex 0.43 for a bit, and faced similar
problems. Lots of stuff about "redundant" equations and other stuff I didn't
understand.

However, I've found that cleaning up your objects when you're done pretty much
solves all my problems. For example, just add a clearObj line to your code
makes it work for me:

\startMPinclusions 
input metaobj; 
\stopMPinclusions

\starttext 
\startMPpage 
newBox.a(\sometxt{hello world}); 
a.c = origin;
drawObj(a);
clearObj a;

\stopMPpage 
\stoptext

I'm not completely sure why this is clearObj a (and not clearObj(a), which
seems to be more logical considering drawObj also takes parentheses), but
that's probably something of the wonderful world of macro "programming".

Hope this helps,

Matthijs