Ken Lapre, who lives near Fredericksburg, Va., has a problem that's common on the outskirts of cities: little choice for Internet service.

I quoted him in last week's column about people whose Verizon MiFi units (cellular Internet devices that create Wi-Fi hot spots for PCs and other gadgets) were downloading unexpectedly large, and expensive, amounts of data (see tinyurl.com/z395jql).

Lapre said he was forced to use his iPad's cellular data service after his 20-gigabyte MiFi data package was used up partway through the month. He asked if there was any way to get an unlimited data plan to replace MiFi.

A: Unfortunately, unlimited data plans tend to be offered only by cable TV and telephone companies that use land lines, and none serve your rural area. And, as you noted, satellite Internet access in your area offers only metered monthly data plans similar to Verizon's MiFi.

Even though you're forced to live with a limited data download plan, you can manage your data differently to avoid overrunning your monthly allotment and paying penalties. The simplest solution is to disconnect your MiFi unit and switch its 20-gigabyte data plan to your iPad. Then turn on the iPad's "personal hot spot" (see tinyurl.com/nnerajh) so that your PC can connect to it via Wi-Fi, and thus gain access to the Internet.

When you're finished using the PC, turn off the iPad's hot spot so that your PC can't use the Internet to download more data on its own and use up your monthly data allotment. (Verizon said this happens if MiFi units are left turned on, because automated PC processes run in the background even if the PC isn't in use.) That should make your data plan last all month.

Q: To improve wireless Internet coverage on the first floor of our house, we set up a Wi-Fi extender unit that uses home electrical wiring to relay the signal from our second-floor PC network. When the booster wouldn't accept the Wi-Fi signal, we called the manufacturer's tech support people, who said our network was corrupted with something called "Koobface." The tech support workers offered to sell us a $100 program they said would fix everything, but my husband was leery and didn't buy it. What should we do?

Linda Haskins, Winter Haven, Fla.

A: Koobface, so-named because it originally spread itself through Facebook messages, is a type of malicious software called a "network worm." It can take over your PC, steal information and spread itself throughout home networks.

Because Koobface first appeared in 2008, it is now well-understood and easily removed. But rather than pay to have it eliminated, download Microsoft's free "Malicious Software Removal Tool," which works with Windows Vista, 7, 8, 8.1 and 10 (see tinyurl.com/oq66pxa). The list of the malicious programs it removes includes Koobface (see tinyurl.com/zj9o79f).

E-mail tech 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 telephone number.