If this happens when compiz plugins are toggled then it might be a simple matter of the MT grabhandles plugin not supporting stop/start unload/reload very well. We used to have similar crashes in unityshell quite frequently.
If this happens when compiz plugins are toggled then it might be a simple matter of the MT grabhandles plugin not supporting stop/start unload/reload very well. We used to have similar crashes in unityshell quite frequently.