Q: Can I continue to use Windows XP safely if I install the for-pay version of Malwarebytes, which is now considered to be antivirus software?

William Parks, Newmanstown, Pa.

A: Readers periodically ask whether they can continue to use the obsolete Windows XP operating system. This is a reasonable question, considering that XP is still used by about 7 percent of all PCs.

The best answer is no. You shouldn't continue to use Windows XP, which was introduced in 2001, because it no longer receives security updates from Microsoft (they were discontinued in 2014.) And XP has already proved to be vulnerable to internet security threats. Microsoft issued an emergency security patch for XP in 2017 after a widespread ransomware attack, in which PC data was encrypted and only released if the user paid a fee.

But can you safely use Windows XP if you take precautions? Yes, but so many precautions are required that most people would find it easier to switch to a newer operating system.

Most advice for Windows XP users has revolved around halfhearted protective measures that might or might not work — install all available XP updates, use current antivirus software and avoid using the old (and flawed) XP-compatible versions of the Internet Explorer browser.

But a more comprehensive list of protective measures has been compiled by a former IBM engineer (see tinyurl.com/mno32gl). He said these precautions will make XP safe for another two to three years. After that there probably won't be any XP-compatible software that still receives security updates. His list includes:

• Never download anything.

• Avoid social-media sites, including Facebook and Twitter.

• Use only the Google Chrome or Mozilla Firefox browsers, and disable vulnerable browser add-on programs (sometimes called plug-ins) such as Java, Flash Player and Adobe Reader.

• Use "whitelisting" software that allows only specified programs to run on the PC and limits your web browsing to only approved websites (see tinyurl.com/ydhud5y4 and tinyurl.com/y8ryl4bb).

• Don't use XP's firewall software, its Media Player audio-video program, or the XP-era versions of the Outlook and Outlook Express e-mail programs — all are vulnerable to tampering. He also recommends using two firewalls — one in your home router and the other on your PC.

• Log in to your PC with a nonadministrator account (see tinyurl.com/y7msv23m), which makes hacking the PC more difficult.

Q: The Mozilla Firefox browser recently stopped working with my printer. The printer still works with Google's Chrome browser and with nonbrowser programs, such as Photoshop CS2. What can I do? Do I need to upgrade from Windows 8.1 to Windows 10?

Jeff Dean, Tucson, Ariz.

A: Because the printer works and you can print with the Chrome browser, the problem probably lies within Firefox. Try altering the Firefox printer settings or changing the typeface Firefox uses to print (see tinyurl.com/k469mzl). If that doesn't work, switch to Chrome. You don't need to upgrade to Windows 10, which causes problems with Photoshop CS2, introduced in 2005.

E-mail tech questions to steve.j.alexander@gmail.com. Include name, city and telephone number.