[NTG-context] TeX run : 8 (vs. 2 ?)

Hi, a ConTeXt document that is typeset under WinXP needs 2 runs. The same document (and the same typescript, map files, font files) when typeset under OSX (Gerbens i-installer used) needs 8 runs!!! Each time it is typeset! For the result looks the same I assume it's a kind of bug. Anybody knows what to do? Thank you, Steffen