though this is extremely old, i have been struggling with this myself, so maybe it will help somebody else searching in the future to "close" the issue:
there seem to be two issues: 1. mrxvt does not (yet) support utf8. if using a utf8 locale, mrxvt will "choke" on it, especially with ncurses apps. if you can live without it within mrxvt, using a "standard" ascii locale is a workaround (works for me: mutt looks nice and smooth again). documented here: http://materm.sourceforge.net/wiki/FAQ/Tips 2. the rxvt term info definitions seem to be somehow problematic, the newer mrxvt uses TERM=rxvt, thus there are further issues within ncurses. using -tn xterm (or equivalent config option for mrxvt) works around this (ex.: it fixes some drawing issues in aptitude). as a side note, i use fvwm, which now supports tabs natively, so i shouldn't need the main mrxvt feature which was a "deal maker" for me back when i chose it, but i am too lazy for now to configure the fvwmtab module :) hope this helps somebody. -- nanok