Due to some altered memory settings in miktex.ini, it is required to refresh the dump files (*.fmt;*.efmt;*.base;*.mem). Normally this happens automatically. But this time MetaPost fails to "recognize" the new memory settings and stops with an error message ("I'm broken. Please show this to someone who can fix can fix"). The workaround is simple: creating new dump files (via MiKTeX Options) solves the problem. For more information, see this bug report.