In my computer repair business, there is a steady flow of PCs that arrive with the same complaint. The owner one day turned on the computer and got an error message such as "Operating System Not Found."

What this means, of course, is your hard drive has gone south, has flown the coop, has bought the farm, has gone to hard-drive heaven. I have written in this space many times that it is not a matter of if, but when, in terms of data loss. Sure, it's possible that you will purchase a computer and never lose a file or a drive, but the odds are the drive will bite the dust if you keep the computer long enough.

The reason for this comes along with the dropping price. Hard drives used to cost thousands of dollars and now are practically given away in Happy Meals.

With the new lower price (a terabyte for a couple hundred bucks!) comes cheaper parts and a reduction in the mean time between failure. You get a lower price, but it doesn't last as long.

We all used to use these 250-meg tapes in the ubiquitous "Colorado" tape drives to back up our hard drives, but today tape drives are impractical for home use. Instead, get yourself an external hard drive that is twice as large as your hard drive and back up your data. Really. I'm not kidding.

One recent customer had her wedding photos on her hard drive with no backup, and it took significant effort to get them back. Another had all of the photos of her children from birth and nearly lost them all. Today we have no negatives, so it is important that you back up your data, especially your photos and documents.

Anyway, how can you tell if your hard drive is heading south? Often you can't. Sometimes there is no warning at all. But sometimes there are a few warning signs. One is a constant whine that wasn't there before. Hard drives should spin up when you turn on your computer, but after that you shouldn't really hear much. If you hear a constant whine, you should back up your data and consider a replacement.

Another sign is clicking and metallic grinding. Drives should not make repetitive clicking noises in normal use. If you are getting that, sooner than later get a replacement in place. Clicking sounds or, worse yet, warning signs from Windows that you have lost data also are sure signs.

Sometimes when your PC is hot and running for a long time, the PC will lock up, but if you let it sit for a few hours it will come back and reboot. That also is a sign that the drive could be going bad (or the PC is full of dust or the fans are not working.) Consider a PC checkup if you see any of these signs.

James Derk is owner of CyberDads, a computer repair firm, and tech columnist for Scripps Howard News Service. His e-mail address is [email protected]