I understand your situation with others using the system, its the same for me :-)
I can't say anything about the smb.conf modification, I guess someone else should comment on that. Or if you would like to file a bug/feature request in trac, with information about how and why, that would allow someone to look at it.
A hard crash seems strange, that would indicate a kernel or hardware error (And makes troubleshooting harder, but you could check dmesg or syslog for any clues after rebooting). For starters, I would try to break down what happens during synchronization of the pictures, and try to pin point the source of the error. I.e. first try running the synchronize command from the command line, checking that the path it uses actually exists and is readable, try synchronizing without pictures - or only a few pictures.