Hi,
Nath is a very complex module, easily broken. If you can privately send me your preamble we might be able to find what was breaking it. Or you can try it yourself: move it up line by line until delimiters don't work anymore: you'll find what makes it bomb :)
OK, I'll try that. At the moment I'm having all kinds of issues with nath (even without any preamble at all), like \binom{\frac 12}{a} not working, \to, \ot and \otto arrows not adjusting to the lengths of their subscripts, etc... and I can hardly imagine that all of these are nath bugs, so maybe something's wrong with my TeX installation. I'm using the latest i-Installer teTeX for MacOS X package (with non-beta ConTeXt version), configuration files unchanged. So if someone else is using nath with Gerben Wieda's teTeX installation, it would be helpful to know if he/she is experiencing similar problems. Anyway, the nath module looks very promising; I'm really looking forward to its next revision! Best regards, Sebastian