Q: I recently renewed my Norton security software, but declined a $10 PC security scan they offered. A while later, a message appeared on my screen warning me of suspicious activity on my PC, and a number to call. I wasn't able to remove the message from my screen, so I called the number. The technician who answered said my PC warranty was up, and that my PC contained thousands of malware programs. He said Microsoft would charge me $500 for his help in removing the malware. When I refused and accused him of hijacking my PC, he agreed to release my PC, which now works again. What's going on and who's responsible?

Dennis Gagliardi, St. Marys, Ga.

A: Congratulations on talking your way out of a common Internet scam. Your PC does have a problem, but it's relatively minor and you can fix it yourself.

What happened? Your PC was temporarily taken over by a single piece of malicious software, which you probably downloaded inadvertently. The malware locked up your PC until you called the number on your screen. The person at the other end, who has no connection to any reputable company, offered to fix a vast collection of imaginary problems on your PC. When you accurately described him as a scam artist, he got cold feet and let you go.

Now that your PC is working, run a full system scan using your existing Norton software and the free version of Malwarebytes (see tinyurl.com/lm3wdcb). Once you eliminate the malware behind this problem, run the security scans every couple of weeks.

Q: I recently got a "BIOHD-8" error code on my Compaq PC. Is this something I can fix myself?

Alan Feuer, Miami

A: That error message is supposed to mean that your hard drive is going bad and needs to be replaced. But with HP computers (Compaq is made by HP), there have been reports of PCs erroneously indicating that the hard drive was failing. In some cases, the problem disappeared when the same hard drive was used with a newer PC. So, rather than replace the hard drive now, continue to watch its behavior for any tangible symptoms of failure (see tinyurl.com/gu8fru7). If some of these symptoms appear, replace the hard drive.

Q: I haven't been able to increase the font size on AOL.com and other websites. What can I do?

Stanley Maisel, Golden Valley

A: You can change the size of the font (alphabet letter style) for all websites you view by adjusting your Web browser. To make the change in the Google Chrome, Mozilla Firefox or Microsoft Internet Explorer browsers, see tinyurl.com/mmxgevd. For the Microsoft Edge browser in Windows 10, see tinyurl.com/gvfc8cn.

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