Plesk issues on Dedicated Servers
From Amen Wiki
If you are familiar SSH Command line access and Plesk is very slow or has stopped responding, the service may just need a restart.
To stop Plesk
/etc/init.d/psa stop
To start Plesk
/etc/init.d/psa start
Other usage options for /etc/init.d/psa include startall stopall restart status
