Have you tried removeing the Gnome configuration for your profile.
some systems, in my experience have have had some strange configuration issues because th Gnome tryies to load the Desktop contents of KDE as WELL as Gnome. This means the that there may be some conflikting thing , e.g KDE kickstart application that may be causing Gnome to reboot nautilus.....
Then again there just might be a problem with nautilus configuration, try looking at the Gnome configs in KDE using the 'Configuration Editor' tool (Thats for Gnome)
This Did happen to me by the way after i moved to Gnome from KDE cause i felt like a change
but that happened. so icheck the configs of the Nautilus and the Panel in the config editor.
try and see what happens.