Last month's commentary about Aero Glass's tendency to heat up your laptop to worrisome levels provoked a lot of email, including pictures of two laptops that had partially melted from running Aero Glass. Some of the email exchanges made me realize that a lot of folks are unaware of a 21st Century reality: overheated computers.

Modern laptops run modern high-speed CPUs, which means hotCPUs. And, as I explained last month, more and more laptops sport an additional special-purpose CPU called a graphical processing unit (GPU) that performs graphical calculations. Also, manufacturers equip modern laptops with at least two--and often more--temperature sensors whose data helps the CPU determine when to turn on the laptop’s case fans and how hard to run those fans. But sometimes those fans aren't enough.

Your processor's temperature varies depending on how hard you're working it. Running business software doesn’t tax the processor of most computers. Programs that require a lot of computation are the real mercury-elevators. For example, a friend told me his laptop would always shuts down when he ran an application that he downloaded from the Internet. The application randomly generated product activation codes for Microsoft Office. (You see, pirates don't have a program that can generate a working activation code, but they do have the code from inside Windows XP that can recognize whether a given string of letters and numbers are a valid product code. So the bad guys just write programs that endlessly generate random strings of letters and numbers, and then pump that string into the pilfered "is a valid activation code?" program from XP.) Checking an activation code is a complex numerical process, so running the product-code generator basically cranks the processor into overdrive and maximizes its heat output. When my friend’s laptop processor maxed out, the CPU exceeded its maximum safe temperature and shut down. Many heavy-duty games crunch numbers like crazy, which is why you'll probably see your big gamer buddy’s computer provisioned with more fans than Madonna.

What can you do to cool off your system? Many things, but the most important is to give it a good housecleaning once a year. Open up all the access panels on your laptop. Remove the hard disk. Open the CD-ROM drive. (Be sure to turn it off first.) Then locate your fan and gently put a toothpick between its fan blades. Now make a trip to your local electronics store and buy a can of compressed air. Use it to blow out all of the crevices and spaces in your laptop. (The toothpick keeps the fans from spinning too fast when the compressed air blows by--you can destroy some fan motors that way.)

Second, stay aware of your system's heat level. Last month, I mentioned the excellent and free SpeedFan application; use it to keep your CPU's temperature visible in your system tray. And while you have SpeedFan loaded, click its S.M.A.R.T. tab, and let it download and analyze your hard disk's diagnostic information. Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) data from hard disks can provide an invaluable early warning of hard-disk failure.

Getting ready to load Windows Vista on your notebook? Great; you'll probably find a lot to like about it. But first, do a "heat tune-up." You'll be glad you did!