I have a small installation of slackware 12.2 that includes only the console programs plus development programs, upgraded to kernel 2.6.35 (the same modularized kernel I'm using with my modified ttylinux-16.3 filesystem) within which I have compiled all of the above-mentioned programs for ttylinux.
The very same mcabber-0.10.3 binary I've compiled for ttylinux works and connects to servers just fine within my small installation of slackware 12.2, so there is nothing wrong with the program itself and its library dependencies (I'm using the very same libraries and programs in both ttylinux and the slackware 12.2 workstation).
What I've done to test whether it is a matter of incompatibility between the programs I've compiled within slackware and the ttylinux crossbuild system (glibc-2.9-based system), I've just created a new filesystem, replacing all of the ttylinux-16.3 libraries and programs outside of busybox with the original slackware 12.2 programs, and I've compiled also bash-4.2 from within slackware 12.2, to exclude completely that possibility. Basically, in this new filesystem, all that is left of your original ttylinux-16.3 are your scripts. Even by doing this, I'm getting the exact same behavior from mcabber-0.10.3 upon connecting to a jabber server, it crashes with error "illegal instruction".
I've run strace (ver. 4.5.15, the one that came with slackware 12.2) on mcabber-0.10.3 within ttylinux-16.3, and even though it seems to find and verify functionality of all library dependencies for mcabber, it mentions at the end "illegal option", while the same strace-4.5.15 run on the same mcabber-0.10.3 within the small slackware 12.2 install does not report that message. So I'm inclined to think that my ttylinux filesystem is just missing some program that instead is present in the small slackware install and that is necessary for connecting to the jabber servers - I just don't know which one it may be. I'll try and post the same question on the mcabber forum and see if they can come up with some useful suggestion.
By the way, the glibc version in slackware 12.2, where mcabber works just fine, is 2.7. so it's not a problem with glibc-2.9 being too old, either.
Thanks again for your wonderful work maintaining ttylinux, I hope you won't ever give up on it (I've read your post, from last year if I recall well, where you were feeling a bit discouraged and were thinking of refraining from releasing further versions).