Your client has been hit with what you think might be a virus. He came into your classroom, muttering about how he cannot get on the internet and crying that his computer keeps doing strange things!
The computer is shutting down at weird times and there are other things going on, such as not being able to get to the internet. Your client says that a window keeps coming up that looks like it is from Microsoft and states that the computer HAS BEEN INFECTED and that he needs to DOWNLOAD THIS ANTIVIRUS PROGRAM. Then, the computer shuts down.
When you ask him about his antivirus program, the client does thinks he has an up-to-date antivirus program on his computer, but isn't sure if it has been updated. He cannot get to the internet to purchase one.
You are coming to the rescue by checking the mechanical parts of the computer to make sure it isn't just a simple fan or overheating problem first. Then, when that doesn't help, you continue by removing the hard drive, installing it to a USB external drive setup, and running your antivirus program through the drive from your computer. You will also be cleaning up the files and prepping the drive so that, when reinstalled, the computer can get onto the internet and the client can purchase that antivirus software (finally!)