Hi Geoff, Could you send the diamond file that causes Chimera to freeze? I'll check it out. If you don't want that file to be seen by others, send it just to me. In older versions of Mac OS I observed that when the X server crashes the X application icons stay on the Dock even though the application has died. The only way to get rid of them was to restart the Dock. I find the process number and kill it and it restarts automatically. % ps -xw | grep Dock 3402 ?? S 0:06.11 /System/Library/CoreServices/Dock.app/Contents/MacOS/Dock -psn_0_393217 % kill 3402 It may be that you can't restart Chimera after restarting the X server because the Dock thinks Chimera is still running. Restarting the Dock should resolve that. I see that Hide X11 removes the window frames from Chimera windows. That looks like a Tk or Window Manager bug. You can iconify all Chimera windows by just iconifying the main window. After using Hide X11 you can get the dialog frames back by pressing the dialog close buttons and then use the menus to bring back the needed dialogs. Ick. Tom