|Would you leave a 300 watt light bulb on 24x7x365?|
You can turn them off you know. Heat and electron flowing causes electronic devices to fail.
Is the power supply actually getting the power on signal from the button through the board?
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, Make an autorun.inf folder on all usb drives.