What to do when a Windows PC won't start

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A day like any other: you're ready to get your compute on, but when you press the power button on your machine, nothing happens. Maybe the screen stays blank, or maybe it shows a blinking cursor and nothing else. Nightmare scenarios race through your mind: big repair bill? Lost data? New PC? (Gasp!)

Don't panic. Put away the sledgehammer. All is probably not lost--at least not yet.

A reader contacted me the other day to ask how she could revive her PC, which she had configured to dual-boot Windows XP and Vista. It seems she ran a popular system-maintenance utility, and the next time she started Vista the machine just cycled between the Vista "Please wait" screen and a blank screen.

The utility vendor's support staff kept saying "We'll get back to you" and never did--surprise! Four days later, she was still waiting to hear back from the company's second-tier support, which initially promised to respond within 48 hours.

She tried to use the System Restore option on Vista's Advanced Boot Options menu, which you access by pressing the F8 key immediately after your PC starts. (For more information on System Restore in Vista, see the article on the Microsoft support site.)

Unfortunately, the system indicated that no restore points were available. It seems when XP and Vista are installed in different partitions of the same hard drive, XP will delete Vista restore points, which it identifies as corrupt.

The Microsoft support site describes a Registry tweak that will prevent XP from deleting Vista and Windows 7restore points on dual-boot systems. The change prevents XP from accessing the partition (or "volume") that Vista or Win7 is stored on, but you will still be able to access the XP partition from the other OS.

Of course, this won't help someone who finds themselves restore-pointless. Fortunately, there are other options. Here's a quick troubleshooting checklist for a failed Windows PC. Most of the information applies to all versions of Windows, but the instructions focus on Vista because those are the systems most likely to experience the problem.

Check the power source and peripherals
If your PC doesn't respond at all, it's easy to neglect the obvious. Is it plugged in? Is the monitor on (and plugged in)? Make sure the outlet the machine's plugged into is working. Try using another power cord. For a laptop running on DC, check the battery to determine whether it's charged.

Once you confirm that the power source is working, unplug everything except the monitor and keyboard, and then press and hold the power button for 15 seconds. This will dissipate any stored charge. Next, unplug everything except the monitor and press the power button. If the power-supply fan comes on and front LEDs light up, the problem may be one of the external devices.

For a laptop, unplug the system, remove the battery, press and hold the start button for 60 seconds, replace the battery, plug the power cord back in, and try starting the machine.

Venture inside the box--with care and caution!
In a perfect world, PC users would never have to remove the machine's case and fiddle with its internal components. But entropy happens, and sometimes a cable or other connection comes loose.

PC technicians use many different techniques to ensure that the power supply, internal drives, plug-in boards, and other motherboard components are working. I'm satisfied just to make sure all the connections are solid and leave the detailed hardware diagnostics to the pros.

Start by unplugging everything from the PC. Then carefully remove its case and touch some grounded metal to ground yourself and avoid generating a static-electricity spark that can fry the PC's circuits when you touch them. Make sure all the cables are firmly in place, especially the cable running from the power supply to the motherboard.

Check the memory modules on the motherboard to ensure they're firmly in place. They have a release clip on either end of their sockets, but be gentle! You can also try disconnecting the internal drives one at a time and restarting the PC after each disconnection to determine whether one of the drives is causing the problem.

The Microsoft Support site describes how to Check your Hard disk for Errors, How to Check for a Memory Problem , and How to Diagnose common device-driver problems

The system powers on, but Windows won't start
Press F8 immediately after turning the machine on, then choose Last Known Good Configuration from the Advanced Boot Options menu that appears. For more on Vista's advanced startup options (including safe mode), see the article on the Microsoft Support