Looking at this screenshot: http://launchpadlibrarian.net/7193652/gnome_system_manager_processes.png it shows that you're running BOINC which uses 100% of your CPU when you're not using it.
The reason why gnome-system-monitor is not displaying it is because you're probably displaying "View > My Processes" while you installed BOINC as a system process.
Looking at this screenshot: http:// launchpadlibrar ian.net/ 7193652/ gnome_system_ manager_ processes. png it shows that you're running BOINC which uses 100% of your CPU when you're not using it.
The reason why gnome-system- monitor is not displaying it is because you're probably displaying "View > My Processes" while you installed BOINC as a system process.