Hello Mojca, I can only guess, since I (do I repeat myself?) don't have MikTeX installed. It seems that you don't have shell-escape or write18 enabled. This feature lets you run external programs from your tex-run. This is a potential security hole, so it is disabled by default. You have two options, enable write18 by using --shell-escape on the command line (see http://www.phys.uvic.ca/Help_Guides/miktex.html#IDX164 ) or tell ConTeXt to do without (that's what I have on live.contextgarden.net) [cont-sys.tex:]
\unprotect \setupoutput [pdf]
this should be [pdftex], not [pdf] (please correct me if I'm wrong)
\runMPgraphicstrue \runMPTEXgraphicstrue
disable these two: % \runMPgraphicstrue % \runMPTEXgraphicstrue [...] Hope this helps. Patrick -- ConTeXt wiki: http://contextgarden.net