I'm an expert at learning things the hard way.

For example, my two-year-old Acer PC had reached the point where it desperately needed a hard drive reformat/Windows reinstall. (For background, read "How to decide when it's time to reformat and reinstall Windows.")

Having been through this process many times before, I backed up all my data, made a list of the programs I'd need to reinstall, located my Windows DVD, and, because I'm a smart cookie, made a backup of all my drivers.

This last is really important, because once you wipe your hard drive and reinstall Windows, your system may have no audio, no Ethernet, no Wi-Fi, and possibly even no USB--all potentially major problems.

Following my own advice from a couple years back, I used the free Semper Driver Backup utility to copy every installed driver to the same external drive that contained all my backed up data. I checked the folder and, sure enough, saw a lengthy batch of driver-looking files. Now I was good to go.

Or so I thought. Once I'd finished reloading Windows, I checked Device Manager and found exactly what I expected: little yellow flags next to a half-dozen drivers. No problem; for each one I clicked Update Driver, navigated to my external drive, and let Windows do its thing.

Except it didn't work. Windows balked at nearly every driver I'd backed up, saying they "weren't digitally signed" or simply weren't compatible with the device in question. D'oh!

And because the problem drivers included Ethernet and Wi-Fi, I couldn't go online to get the correct ones.

Thankfully, Acer makes it fairly easy to find model-specific drivers via its support site, so I was able to use another PC to download what I needed. For the record, most of these drivers had their own installers, so it's possible Windows needed more than just the "raw drivers" for the various hardware elements.

Interestingly, I had one moment of serious concern when the machine wouldn't even read my external hard drive, meaning there was no way to access any drivers. Turns out I'd plugged into the sole USB 3.0 port, which itself required a driver that wasn't present. But the USB 2.0 ports worked just fine with Windows' stock drivers.

The moral of the story: When you're prepping for a reformat, head to the system maker's site and download all the drivers for your machine, because a driver backup may not provide everything you need.

And this is definitely one point in favor of Windows 8, which has that awesome refresh feature. In theory, a lot of these shenanigans will be a thing of the past.

Contributing Editor Rick Broida writes about business and consumer technology. Ask for help with your PC hassles at hasslefree@pcworld.com. Sign up to have the Hassle-Free PC newsletter e-mailed to you each week.