Q: It seems more and more every day that computing is less and less secure. Each day a new “impossible” threat is shown to be possible.

With that thought in mind, I’d like to turn to the Malaysia Flight 370. Is it possible for a passenger in coach to hack into an airplane’s onboard computer system and take over control of the aircraft?

— Brian Lynch, Bellingham

A: I’m not going to say anything is impossible when it comes to computer security. But I very much doubt that anyone has hacked into an airliner’s computer system, and especially not into an autopilot system.

The autopilot systems on airliners have been designed to be controlled only by commands entered inside the cockpit.

While some people in the blogosphere — and even in some traditional news outlets — have suggested that such hacking is difficult but possible, most security experts say that hacking is very unlikely.

“It’s extremely, extremely far-fetched,” David Kennedy, CEO of cybersecurity firm TrustedSec, told NBC News. “Knowing what we know about airplanes, it is very unlikely.”

According to Kennedy, taking control of an airliner would require much more than getting access to a single computer system. “It isn’t about hacking a single system,” he said. “You’d need to spend years learning about multiple systems from different companies, and software that is frequently updated.”

Q: I have a custom-made desktop PC. I run Windows 7 on it. I routinely run Avast and Malwarebytes scans on it.

A recent Malwarebytes scan detected seven items. After the scan I looked at the report and it said the items were Trojans. I had the malware program remove them.

Now, every time I go to shut off my computer, I get the message to not shut off my computer or interfere with Windows updating 1 of 1 update. This is normal update behavior, so I merely shut off the monitor.

However, since the malware scan, Windows has done the 1 of 1 update four times. I just now looked at the update history, and it has tried to install Internet Explorer 11 at least a dozen times without success.

What is going on, and what should I do? I hope it doesn’t require doing things to my registry, because I have no idea how to do that safely, and I don’t want to ruin my computer.

— Michelle, Olympia

A: Windows update problems are not uncommon, and it can be really difficult to track down the cause. In this case, I’d suggest trying to go around the problem by manually installing the current version of Internet Explorer 11. Just go to windows.microsoft.com/en-us/internet-explorer/download-ie and follow the instructions.

Q: For about a year, my AVG (free) anti-virus software has come up with cookie warnings almost daily about EarthLink 5.0. I had used the EarthLink service up to four years ago, but now I use Comcast. I don’t recall ever seeing this message back when I was on EarthLink.

When I attempt to delete these cookies by right-clicking on it on the AVG window’s line I get the report, “The path does not exist or is not a directory.” No further options are given.

Sometimes a “Cookies” window shows up listing EarthLink 5.0 in the left column, followed by my old address used on EarthLlink. When I try to delete it, I get a window saying it cannot be deleted.

I have XP Home on a 10-year-old Dell. I have on order a new Dell with Windows 7. I don’t want to transfer this EarthLink monster onto my new computer! I’d appreciate your suggestions on a cure.

— Charles Bagley, Seattle

A: The first thing to do is to make sure there is no EarthLink software still on your computer. To do so, go to the Control Panel and launch the Programs and Features utility. Uninstall any EarthLink applications you find.

Next, open a command prompt and type Msconfig.exe
. If you see any EarthLink software in the Startup section, disable it.

Reboot your computer, and if you still are receiving those warnings, it’s likely that remnants of the software and/or cookies are still on your system. Your choice is either to configure AVG to stop popping up notices, while still providing protection, or to clean up your computer. You can try doing that by uninstalling and then reinstalling your browser programs.

If that doesn’t work, it may take reinstalling Windows. Since you’re getting a new computer, however, I wouldn’t worry about it. Just moving your data files over to a new computer won’t bring that problem along with it.

Questions for Patrick Marshall may be sent by email to pmarshall@seattletimes.com or pgmarshall@pgmarshall.net, or by mail at Q&A/Technology, The Seattle Times, P.O. Box 70, Seattle, WA 98111. More columns at www.seattletimes.com/

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