Hi,
GNOME is crashing when logging with ROOT but not with a regular user. The crashing problem is something with the PANEL.

Is there a way to reinstall GNOME or like to erase all the files of the current setting of GNOME ? thk !

i'm not too familier with gnome (i use kde primarily), however, whenever I wanted to "clear the slate" as a user under kde, I would issue the command "rm -rf ~/.kde". Check your root's home directory for something like "~/.gnome" and make sure you back up the important stuff and clear it. The next time you start, you will have to re-configure everything.