I do not know, what you have changed in your /etc/httpd/conf/httpd.conf, but you must have found this header:
#------------------------------------------------------------
# DO NOT MODIFY THIS FILE! It is updated automatically by the
# SME Server software. Instead, modify the source template in
# an /etc/e-smith/templates-custom directory. For more
# information, see http://www.e-smith.org/custom/
#
# copyright (C) 1999-2003 Mitel Networks Corporation
#------------------------------------------------------------
If you have installed your eGroupware the same way by editing this conf file by hand, it is very likely, that you will kill the eGroupware setup, too.
However, if you used a setup or installation Howto specifically for SME, this would certainly restore a working version.
But why do you not backup the existing conf file, use the above expand-template command and compare the new conf file to find the difference between both of them?
You can do this while running SME, if you do not restart the httpd daemon.