Facebook requires you to provide a different “primary” e-mail address for each Facebook account. (Marci Schmitt — Associated Press file/The Minnesota Star Tribune)

Q: When I first signed up for Facebook, I gave my work e-mail. Later, I got a personal Gmail address and signed up for a second Facebook account that would be mine alone. But over the years, 99% of my Facebook activity has been on my "company" account. So, when I retire, I'd like to take the company Facebook account with me by switching it from my work e-mail address to my Gmail.

To do that, I deactivated my second Facebook account, thinking that would allow me to shift my Gmail address to my company account. But Facebook won't let me make the switch. I get an error message that says my Gmail is affiliated with another Facebook account. What can I do?

Devere Curtiss, Colorado Springs, Colo.

A: Facebook requires you to provide a different "primary" e-mail address for each Facebook account. But there are two ways to change which e-mail address goes with which account:

• Delete your second Facebook account. That will "free up" your Gmail address so it can be used with your company Facebook account.

So far, you've only "deactivated" the second account. Under Facebook's rules, deactivation means the account still exists and can be reactivated at any time — which means the account still retains a hold on your Gmail address. But if you "delete" the second Facebook account, it will cease to exist and release your Gmail address. (To permanently delete a Facebook account, see tinyurl.com/ce438aa). Note that it will take Facebook 30 days to delete your second account. After that, you can add your Gmail address to your company Facebook account as the "primary" e-mail. (To add or delete a Facebook account's e-mail address, see tinyurl.com/yyfcmawt).

• Keep both Facebook accounts, but change their e-mail addresses. To do that, create a new Gmail address. (Go to Gmail.com and click "use another account." On the next screen, click "create account.") Add this new address to your second Facebook account as the primary e-mail. Then delete your original Gmail address from the second Facebook account and add the address to your company Facebook account as the primary e-mail.

Q: I have a Dell XPS 8900 desktop that has to go through the PC startup cycle three times in order to turn on. But, once started, the PC works perfectly. I've installed all Windows 10 updates, run diagnostic software and updated the PC's BIOS (Basic Input/Output System software), but nothing has helped. This started happening after I opened the PC's case and removed dust with a hand vacuum cleaner. (I've done it before, and am always careful not to let the vacuum cleaner touch any computer parts.) What wrong?

Richard Wilde, Minneapolis

A: I think your vacuum cleaner has damaged the PC's main circuit board, causing it to malfunction during startup. Eventually, the PC may not start at all.

Why? A static electrical charge builds up on the end of a vacuum cleaner's nozzle. Even if the nozzle doesn't touch the circuit board, the electrical charge can jump the gap between them and permanently damage sensitive electronic components. The safe way to clean the inside of a PC is to buy a can of compressed air ($3 to $8.) I think your only options are to replace the main circuit board ($110 to $125, plus labor) or buy a new PC. But first, get a second opinion from a repair shop.

E-mail questions to steve.j.alexander@gmail.com or write to Tech Q&A, 650 3rd Av. S., Suite 1300, Minneapolis, MN 55488. Include name, city and number.