Sorry,no backtrace(I did have one before but I compiled out debugging on next compile).I'm getting similar issues with ratpoison and wmi.
Ratpoison: Segaults when switching windows,which is like swtiching to another workspace in ratpoison terms.Also doesn't start from an xterm/gnu screen. i.e acts like it is loading then gives up.
Wmi: Same thing,when switching a window it segaults...and some times segfaults without me touching it.
What I do at the moment is to either run amulecmd/daemon (which segaults occasionally also) or I run amulegui in a seperate xserver under wmi and don't switch any windows.My feeling is that I have optimisations on and it is buggering it up.I am going to try compiling latest cvs with debugging on and I will post a backtrace if it keeps happening.Also I have heard that the webserver is fixed in new cvs so that is reason enough to try

Oh btw am using wx gtk 2.5.3 with gtk1/no unicode.