i have some dim recollections about sbox being designed for 8.04 -- that would be exactly two yeasr before the current 10.04. but i may be wrong.

as for the recurrent
mmap: operation not permitted
i recollect a similar error message when using flash with jffs. jffs apparently lacked (lacks?) features necessary for mmap.
what file systems are you guys using?

in case of eg
Setting up packagename (version) ...
mmap: Operation not permitted
dpkg: error processing packagename:
subprocess post-installation script returned error exit status 255

you could check
/var/lib/dpkg/info/packagename.postinst
that's the script executed, for anything interesting.

although from the numerous mmap errors, i guess it has to do with either the file system or a missing variable below /sys or /proc.