|Open it up and see if it needs a cleaning. Check all the fans, including the power supply fan and input holes. Do not use a vacuum cleaner to clean, Use a can of compressed air. It might be a problem with the CPU to heatsink thermal paste.|
FWIW to XP users: When you click on the 'Command Prompt' you are just causing the 'Command prompt' to be displayed. This prompt gives you access to NTVDM.EXE, the 'NT Virtual DOS Manager'.