Sorry for late reply, but i was on a leave for nearly two weeks.
I corrected the asterisk.asterisk bug, and added check if group exists.
But you should know how it was supposed to work: During 10.04 install we have to install lmce-asterisk BEFORE asterisk itself as it provides asterisk-config files. If we do install asterisk first it will install it's default config package which conflicts with lmce-asterisk. But some parts of asterisk postinst need asterisk to be installed to work. That's while the second half of the postinst script checks if the asterisk binary is already there, which is not the case on a new install where lmce-asterisk is installed during mce-install.sh progress. So it installs lmce-asterisk without doing some of the config, and then installs asterisk itself. During firstboot script (on, as you might imagine, your first reboot after installation) the postinst is called once again, but this time asterisk binary exists and lmce-asterisk does the rest of it config tasks. Asterisk package installs group and user, so it should never happen that this part of script is run and that user of group does not exist.
Of course i only speak of new installations above. Older 10.04 installations which already had broken freepbx installed these scripts will not work. Purge (PURGE, not simply remove) everything that has to do with asterisk (pluto-asterisk, asterisk-pluto, asterisk, freepbx, ...) and only install lmce-asterisk should do the trick for the older cores ...
So may i ask if it's possible that all of you that run into trouble with group not existing had a core where asterisk was already installed before installing lmce-asterisk package ?