Almost every other day our web server (with Plesk 7.5) freezes up and I need to reboot the server to get things up and running again. All websites and email stop being served and I can't log in via SSH. Does this type of freeze up usually occur because of a hardware issue or is it something Plesk-related? I can't find anything in the server's error logs to tell me why these crashes occur... this is very annoying, especially when it happens over the weekends, when we are offsite. Any thoughts?