The screen has turned black on my wife’s all-in-one PC, a desktop model on which the screen and computer are a single unit. Only the cursor arrow is visible on the screen of her HP Omni model 120. What can we do? — Renato Bunal, Jacksonville, Florida

If you’re lucky, the problem can be solved simply. First turn off the PC and disconnect all accessories, such as USB flash drives or camera memory cards. Then unplug the power cord and hold down the PC’s power button for about 15 seconds. Reconnect the power cord and turn on the computer.

If that doesn’t work, there’s other troubleshooting you can do, even though you can’t see anything on the screen.

If you hear a beeping sound during start-up, HP says a component inside the PC may be loose. While you could open up the computer case to look, I’d recommend letting a repair shop do it. Even a little static electricity from your body could wreck the sensitive electronic components.

If instead you hear the PC’s cooling fan running during start-up, HP says you’ll need to use keyboard commands to adjust either the PC’s BIOS (basic input-output system) software or its power-management program. There’s no room for error in these keyboard commands, so you’ll need to view HP’s precise directions on another computer (see tinyurl.com/ofqayb3).

While at the St. Pete-Clearwater International Airport in Florida, I tried to access the airport’s free public Wi-Fi network with my Nexus 7 tablet computer. The connection icon kept spinning, but I never got connected. Is this a problem with my tablet or with the signal strength of the Wi-Fi network? — Shirley Duerr, La Porte, Indiana

It’s possible that you were too far away from the nearest airport Wi-Fi antenna, or that the Wi-Fi network was loaded to capacity at the time you were trying to use it. But the connection problem also could be related to the way the Wi-Fi system is set up.

St. Pete-Clearwater International Airport’s website (see tinyurl.com/mpewtp7) says its Wi-Fi works best with Microsoft’s Internet Explorer browser, which isn’t available for your Nexus 7 tablet that uses Google’s Android operating system. Next time, try one of the other browsers that’s available for your tablet (see tinyurl.com/ogqvp7b).

Note: Neil Longhenry points out that there are some download issues with the Free Audio Converter 2014 (tinyurl.com/pc5e4om) that I recommended last week for changing audio book files to the MP3 format.

Readers should check the “custom installation” or “I do not accept” buttons to opt out of unwanted add-on software. Skip the “upgrade now” offer that includes additional software.

Steve Alexander covers technology for the Minneapolis Star Tribune. Write to him at Tech Q&A, 425 Portland Ave. S., Minneapolis, Minn. 55488-0002 or email steve.j.alexander@gmail.com. Include a full name, city and phone number. Questions are answered only through his column.