Joyce V's computer is having trouble with security programs--a strong indication that her computer may be infected with malware.
Malware, once it has infected your PC, has a way of protecting itself. It may not want you to install a new antivirus program--or update your current one. So you need to scan your hard drive in a way that gets around the malware. The simplest way to do that is to do the scan outside of Windows.
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Luckily, there are several bootable malware scanners. You put one of these on a CD or a flash drive, boot from that, and scan your hard drive. If they find something, they'll remove it.
I'm recommending Kaspersky Rescue Disk and the F-Secure Rescue CD, because they're both easy to use and come from companies that have done well in testing. If you're really worried, use one, then the other.
I strongly recommend that you use a different computer to download and prepare these programs. And no, you can't simply burn the files to a CD or copy them to a flash drive.
Both programs download as .iso files. When you double-click an .iso, there's a good chance that a program will come up and walk you through the simple process of burning the CD (the process is little more than putting in a CD and clicking OK). If nothing like that comes up, you'll need to download and install an iso-burning program like Active@ ISO Burner, then double-click the file again.
Kaspersky makes it easy to install their "disk" onto a flash drive. In addition to the .iso file, download the Utility to record Kaspersky Rescue Disk 10 to USB devices. With the flash drive plugged in, run that program.
For F-Secure, you'll need to download the Universal USB Installer in addition to F-Secure's .iso file. Run the program, and in Step 1, select F-Secure Rescue CD (it's near the bottom of a very long list). You can figure out the rest from there.
One more point: With Kaspersky, make sure you click the My Update Center tab and update the database before you run the scan. F-Secure updates automatically.
Contributing Editor Lincoln Spector writes about technology and cinema. Email your tech questions to him at firstname.lastname@example.org, or post them to a community of helpful folks on the PCW Answer Line forum. Follow Lincoln on Twitter, or subscribe to the Answer Line newsletter, e-mailed weekly.
This story, "When your PC is likely infected" was originally published by PCWorld.