I hope nobody flames me for this i'm just wanna inform i may be way off base (I am an Xbox NOOB)
I had my xbmp shares werking great then i installed a new version xbmp and nadda well in all of this i started using xbmped which seemed to be the saviour for not having to look through all those lines of xml well after furiously fighting to get either relax or smb werking i finally got relax werking after manually editing the config.xml I was so happy so i went into xbmped to edit the rest of my shares i saved transfered and then boom nothing again (wanna talk about i anger I'm suprised my xbox survived it wasn't a nice scene) anyways turns out that xbmped lower cases the share lines when u save and Fu**s your shares cause when i went back and changed it to $ROOT$ versus $root$ no problems
I'm thinking this must be the same case with smb but not tested yet
Well hope this helps someone out there