pk-command-not-found 100% CPU

I can't tell why, but for some version / distrib of Linux, from time to time, one can experience a 100% CPU load. Doing a top shows that pk-command-not-found is using the CPU...
pk-command-not-found is here /usr/libexec/pk-command-not-found
It is called by /etc/profile.d/PackageKit.sh
It should launch a window asking the user to install a package containing the requested command which wasn't found by the system.
There is another way to get an error message.
Edit  /etc/profile.d/PackageKit.sh
change runcnf=1 to runcnf=0 at the beginning.
Then you'll get  bash: xxxx: command not found
Where xxxx will be the command name that was not found.