16 PC mysteries solved!

Our digital detectives uncover the truth behind some of tech's most baffling questions.

Though your monitor may be malfunctioning, the likelier reason why your display occasionally blacks out when you plug in an HDMI cable and then comes back on 5 to 10 seconds later is that your devices are completing the HDCP handshake. The same thing can happen when you bring your monitor back from sleep mode, as the HDCP handshake protocol must be completed every time your HDMI cable comes back up to full voltage.

HDMI devices occasionally fail the HDCP handshake due to a transmission error or a surge in voltage, so if your monitor blacks out and stays black when you plug in an HDMI cable, switch inputs to HDMI, or bring the monitor back from sleep mode, you'll probably have to power-cycle your display or completely restart your PC.

Why does my OS hide some of my critical system files?

The goal is to make it harder for untrained users to modify or delete them, and thereby cause a system error. The precaution is sensible because most people shouldn't tamper with those files (like config.sys).

If you're curious to see what files and folders are hidden on your Windows PC, here's how to peek behind the curtain.

Open Windows Explorer, and navigate to Tools, Folder Options under the File menu. Windows Vista and Windows 7 disable this menu by default; to make it appear, hold down the Alt key. After opening the Folder Options menu, select the View tab and click the Advanced Setting menu; then find the setting that controls how Windows handles hidden files and folders. Enable the Show Hidden Files, Folders and Drives option, and you should be able to see all of the hidden files and folders on your PC.

After finding the file you were looking for and making all necessary changes, consider disabling the option. Leaving your critical system files visible in Windows Explorer in­­creases the chance that someone will accidentally move or delete one of them, leading to an even greater mystery when your PC suddenly fails to boot properly one day.

In what ways does USB 3.0 differ from USB 2.0?

USB 3.0 data transfers have a theoretical maximum speed of 5 gigabits per second, in contrast to the theoretical maximum speed of 460 megabits per second of USB 2.0. Though you probably won't obtain 5-gbps transfers during daily use, you should find that you can move files significantly faster via USB 3.0 than via USB 2.0.

Transferring data between USB 3.0 devices is also more efficient, because USB 3.0 permits simultaneous data transfers in both directions; USB 2.0 devices can transmit data in just one direction at a time. Of course, to take advantage of these upgrades you'll have to invest in new USB 3.0 devices and cables. Though USB 3.0 is backward-compatible and will work with all old USB 2.0 gear, you must buy a USB 3.0 cable if you want your new USB 3.0 devices to exchange data at full speed.

Why do I need administrator access for some tasks?

Why do I need administrator access for some tasks?

It's a security precaution. Windows requires you to have administrator access in order to modify or delete files, if doing so might affect other people who use the computer. This usually isn't a problem if you set up the PC yourself, since the primary account on any Windows machine is assigned administrator privileges by default; but if you need access to your PC's administrator account without a password (if you bought the PC used, for example) you could be in a pickle.

Normally, gaining administrator access in Windows when you don't know the password to the account entails either reinstalling Windows or using third-party software like the Offline NT & Password Editor to reset the password. PCWorld Contributing Editor Lincoln Spector has written about this issue extensively in his Answer Line column, and you can find his advice on using the Offline NT & Password Editor to gain administrator access.

Fun fact: A hidden administrator account on every Windows 7 PC has privileges that supersede any other user's--and disables all User Account Controls by default. To see it, you must first log in to your Windows 7 PC with an account that has administrator access. From there, right-click the Command Prompt application in your Applications folder and select Run As Administrator. Once the command prompt is open, type net user administrator /active:yes and press Enter. If the command executes successfully, you should be able to exit the Command Prompt, log out of your Windows account, and see the now-visible Administrator account. To cloak it again, follow the same process, changing the Command Prompt entry to read net user administrator /active:no.

Why do I have to reactivate software after upgrading my motherboard?

Most programs link their serial key to the computer you install them on­--and most software vendors tie your unique product key to your PC's MAC address, which your ethernet adapter generates. Some apps remain tied to the serial volume number of your hard drive, but many vendors prefer to use the MAC address be­­cause it is unique to your PC and is easy to transmit to the vendor's website when you register your software online. The ethernet adapter is usually part of the motherboard; when you up­­grade the board, you obtain a new MAC address, and many of your applications must be reactivated.

To combat software piracy, some PC games require you to reactivate them and to verify your identity after a hardware change. Also, some game publishers now require players to be constantly connected to the publisher's servers to play their games.

What is a DisplayPort connection, and how does it affect me?

If you recently purchased a new PC or monitor, you may be mystified by the "DP" or "Display­Port" connection on your new device. This component is exactly what it sounds like: a digital multimedia interface for shuttling data between your PC and your display.

Introduced in 2008, DisplayPort is an open industry standard that companies such as Apple, HP, Intel, and Samsung support. But we have VGA, DVI, HDMI, and now Thunderbolt cables for connecting computers, tablets, and smartphones to monitors and HDTVs. So why should you use DisplayPort instead of a standard DVI cable?

In the first place, the technology is just plain better. DisplayPort can deliver display data to your monitor or HDTV more efficiently than DVI or VGA can, because it transfers signal data to your display in discrete packets rather than in a steady stream. Each data packet contains its own time stamp, which helps your devices assemble the data more easily into what they're supposed to display on screen. The data-packet approach also reduces distortion and image degradation, and it allows developers to modify how DisplayPort transmits their data. DisplayPort cables can carry audio data as well as video data, and they're compatible with most popular display interfaces, if you're willing to purchase an adapter. Consequently you can hook up your new graphics card with DisplayPort connectors to an old VGA/DVI monitor, though most major manufacturers plan to phase out VGA and DVI in the next decade in favor of DisplayPort.

In the long term, this is good news for PC owners, in part because the DisplayPort standard is open and royalty-free (which should en­­courage competition in the market and lower prices). Also, DisplayPort connectors are more powerful and easier to hook up than DVI or VGA cables; instead of fiddling with tiny thumbscrews or worrying about bending a bunch of minuscule pins, you can quickly plug a (significantly smaller) DisplayPort cable into the back of your devices.

Why do certain apps always run at startup?

You may have told them to­, or they may have assumed that you would have done so if you'd thought of it. Free programs such as iTunes, Spotify, and Steam are particularly aggressive about configuring themselves to launch automatically during startup; but some premium paid software suites (like Adobe's) are similarly presumptuous.

Of course, having apps for input devices, antivirus protection, and other critical functions run at startup is a good thing, even if they cause Windows to boot a little slower.

The setting for telling a program when to start up is usually located in the application's Preferences, Tools, or Options menu; consult your program manual for specific guidance.

If you can't stop a program from launching at startup from within the program itself, edit the Windows startup sequence. Click the Start button and type msconfig in the search box. This should open your PC's System Configuration utility, where you can change how your system boots and what applications and services it launches at startup. Select the Startup tab, scroll through the list of programs, and uncheck everything that you don't want to start automatically. If the program you want to halt doesn't appear in the System Configuration utility, don't panic; PCWorld Senior Editor Loyd Case points out that a few applications use the Windows Task Scheduler to launch themselves during startup, so you'll need to open the Windows Task Scheduler and disable them manually.

It's a good idea to let programs that you don't recognize (such as the Default Manager and Java Platform Updater) run automatically to keep your PC purring along smoothly. If you run into trouble, simply return to the System Configuration utility and let the troublesome application launch during startup.

This story, "16 PC mysteries solved!" was originally published by PCWorld.

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